Studies on Adrenoceptors Involved in Regulation of Sodium Transport in Frog Skin

최봉규,김경근,김흥규,국영종,Choi Bong-Kyu,Kim Kyung-Keun,Kim Heung-Kyu,Kook Young-Johng The Korean Society of Pharmacology 1986 대한약리학잡지 Vol.22 No.1

본 연구에서는 개구리(Rana nigromaculata)의 피부에 있어서 전위차(PD), 단락전류(SCC) 및 total skin conductance(TSC)에 미치는 제종 adrenergic agonist 및 그 차단제의 영향을 관찰하여 개구리 피부에 adrenoceptors의 존재를 확인하고 Na 수송에 있어 그들의 역할을 구명코자 하였다. 1.Norepinephrine(NE, $6{\times}10^{-8}-6{\times}10^{-5}M$), phenylephrine($PE,5{\times}10^{-6}-5{\times}10^{-4}M$)의 PD 및 epinephrine(Epi, $5.5{\times}10^{-7}-5.5{\times}10^{-5}M$)의 PD 및 SCC 증가효과는 약물의 투여농도에 비례하였으며, Epi의 최대효과는 NE나 PE의 것보다 약하였다. 2. 이러한 PD 및 SCC의 증가효과는 alpha 1 adrenoceptor 차단체인 prazosin $2{\times}10^{-6}M$에 의해서 억제되었으며, 특히 Epi의 증가효과는 불가역성 alpha receptor 차단제인 phenoxybenzamine $3.3{\times}10^{-5}M$에 의하여 완전히 차단되며 대량의 Epi에 의해서는 PD 및 SCC의 감소를 초래하였다. 3. Beta adrenoceptor agonist인 isoproterenol$(5{\times}10^{-7}-5{\times}10^{-6}M)$에 의해 농도증가에 비례한 PD 및 SCC의 감소가 일어났으며, 이는 선택적 bete receptor 차단제인 propranolol $4{\times}10^{-6}M$에 의해 차단되었다. 또한 Epi의 PD 및 SCC 증가효과는 propranolol $4{\times}10M$에 의하여 강화됨을 볼 수 있었다. 4. Alpha 2 adrenoceptor agonist인 clonidine 및 guanabenz도 PD 및 SCC의 증가를 가져왔으며 이러한 효과는 alpha 2 receptor 차단제인 yohimbine에서 보다 Alpha 1 receptor 차단제인 prazosin에 의해 더 잘 억제되었다. 이상 실험의 결과 개구리 복부피부에도 포유동물에서와 같이 adrenergic alpha 및 beta receptor가 존재하며 alpha receptor는 PD 및 SCC의 증가를, beta receptor는 PD 및 SCC의 감소를 매개하여, 개구리 피부의 Na 수송에 있어 adrenergic system이 중요한 조절작용을 하고 있음을 알 수 있었다. 그러나 여기에 관여하는 alpha receptor는 다른 포유류에서와 같이 alpha 1 및 alpha 2 adrenoceptor로 구분할 수는 없었다. To ascertain the existence of various adrenoceptors involved in active transport of sodium in the frog skin and to delineate their physiological roles, the influence of various adrenergic agonists and antagonists on the potential difference (PD), short-circuit current (SCC) and total skin conductance (TSC) of the isolated frog skin of Rana nigromaculata were investigated. PD and SCC were determined with Ussing's technique. Drugs were administered to the serosal side of the skin. Experimental results were summarized as follows: 1. The responses to norepinephrine (NE, $6{\times}10^{-8}-6{\times}10^{-5})M$), phenylephrine (PE, $5{\times}10^{-6}-5{\times}10^{-4}M$) and epinephrine (Epi, $5.5{\times}10^{-7}-5.5{\times}10^{-5}M$) were characterized by marked elevation of PD & SCC in dose-related fashion, but the maximal effect attained by Epi was less than those of NE and PE. 2. These increments of PD & SCC were significantly inhibited by prazosin $(2{\times}10^{-6}M)$, a speciflc ${\alpha}_1$-adrenoceptor blocker. The stimulatory effect on PD & SCC were completely abolished by phenoxybenzamine (PBZ, $3.3{\times}10^{-5}M$), an irreversible ${\alpha}$-adrenoceptor blocking agent. Furthermore, with a larger doses of Epi produced marked decline of PD & SCC after the PBZ pretreatment. 3. Isoproterenol (ISP), a ${\beta}$-adrenoceptor agonist, in concentrations ranging from $5{\times}10^{-7}$ to $5{\times}10^{-6}M$ produced dose-related decrease in PD & SCC, which could be abolished by pretreatment with propranolol $(4{\times}10^{-6}M)$, a specific ${\beta}$-adrenoceptor blocker. It was further noted that the effects of Epi on PD & SCC were markedly potentiated by Propranolol pretreatment. 4. Clonidine as well as guanabenz produced increases in PD & SCC and these effects were inhibited more specifically by prazosin pretreatment than by yohimbine. These results indicated that there exist in the frog skin two distinctive types of adrenoceptors, ${\alpha}$ and ${\beta}$, which roughly corresponds to those in mammals, and that the ${\alpha}$ type of adrenoceptors mediate the stimulation of PD & SCC, whereas ${\beta}$-adrenoceptors mediate the inhibition. However, based on evidence at hand, no conclusion could be drawn on the subtype of ${\alpha}$-adrenoceptors which is involved in the stimulation of sodium transport in the frog skin.

개구리 피부에 있어서 Na 수송을 조절하는 Adrenoceptors에 관한 연구

최봉규(Bong Kyu Choi),김경근(Kyung Keun Kim),김흥규(Heung Kyu Kí,m),국영종(Young Johng Kook) 대한약리학회 1986 대한약리학잡지 Vol.22 No.1

본 연구에서는 개구리(Rana nigromaculata)의 피부에 있어서 전위차(PD), 단락전류(SCC) 및 total skin conductance(TSC)에 미치는 제종 adrenergic agonist 및 그 차단제의 영향을 관찰하여 개구리 피부에 adrenoceptors의 존재를 확인하고 Na 수송에 있어 그들의 역할을 구명코자 하였다. 1.Norepinephrine(NE, 6×10^-8-6×10^-5M), phenylephrine(PE,5×10^-6-5×10^-4M)의 PD 및 epinephrine(Epi, 5.5 ×10^-7-5.5 ×10^-5M)의 PD 및 SCC 증가효과는 약물의 투여농도에 비례하였으며, Epi의 최대효과는 NE나 PE의 것보다 약하였다. 2. 이러한 PD 및 SCC의 증가효과는 alpha 1 adrenoceptor 차단체인 prazosin 2×10^-6M에 의해서 억제되었으며, 특히 Epi의 증가효과는 불가역성 alpha receptor 차단제인 phenoxybenzamine 3.3 ×10^-5M에 의하여 완전히 차단되며 대량의 Epi에 의해서는 PD 및 SCC의 감소를 초래하였다. 3. Beta adrenoceptor agonist인 isoproterenol(5 ×10^-7-5×10^-6M)에 의해 농도증가에 비례한 PD 및 SCC의 감소가 일어났으며, 이는 선택적 bete receptor 차단제인 propranolol 4×10^-6M에 의해 차단되었다. 또한 Epi의 PD 및 SCC 증가효과는 propranolol 4×10M에 의하여 강화됨을 볼 수 있었다. 4. Alpha 2 adrenoceptor agonist인 clonidine 및 guanabenz도 PD 및 SCC의 증가를 가져왔으며 이러한 효과는 alpha 2 receptor 차단제인 yohimbine에서 보다 Alpha 1 receptor 차단제인 prazosin에 의해 더 잘 억제되었다. 이상 실험의 결과 개구리 복부피부에도 포유동물에서와 같이 adrenergic alpha 및 beta receptor가 존재하며 alpha receptor는 PD 및 SCC의 증가를, beta receptor는 PD 및 SCC의 감소를 매개하여, 개구리 피부의 Na 수송에 있어 adrenergic system이 중요한 조절작용을 하고 있음을 알 수 있었다. 그러나 여기에 관여하는 alpha receptor는 다른 포유류에서와 같이 alpha 1 및 alpha 2 adrenoceptor로 구분할 수는 없었다. To ascertain the existence of various adrenoceptors involved in active transport of sodium in the frog skin and to delineate their physiological roles, the influence of various adrenergic agonists and antagonists on the potential difference (PD), short-circuit current (SCC) and total skin conductance (TSC) of the isolated frog skin of Rana nigromaculata were investigated. PD and SCC were determined with Ussing s technique. Drugs were administered to the serosal side of the skin. Experimental results were summarized as follows: 1. The responses to norepinephrine (NE, 6×10^-8-6 ×10^-5)M), phenylephrine (PE, 5×10^-6-5×10^-4M) and epinephrine (Epi, 5.5 ×10^-7-5.5 ×10^-5M) were characterized by marked elevation of PD & SCC in dose-related fashion, but the maximal effect attained by Epi was less than those of NE and PE. 2. These increments of PD & SCC were significantly inhibited by prazosin (2×10^-6M), a speciflc α₁-adrenoceptor blocker. The stimulatory effect on PD & SCC were completely abolished by phenoxybenzamine (PBZ, 3.3×10^-5M), an irreversible α-adrenoceptor blocking agent. Furthermore, with a larger doses of Epi produced marked decline of PD & SCC after the PBZ pretreatment. 3. Isoproterenol (ISP), a β-adrenoceptor agonist, in concentrations ranging from 5 ×10^-7 to 5×10^-6M produced dose-related decrease in PD & SCC, which could be abolished by pretreatment with propranolol (4 ×10^-6M), a specific β-adrenoceptor blocker. It was further noted that the effects of Epi on PD & SCC were markedly potentiated by Propranolol pretreatment. 4. Clonidine as well as guanabenz produced increases in PD & SCC and these effects were inhibited more specifically by prazosin pretreatment than by yohimbine. These results indicated that there exist in the frog skin two distinctive types of adrenoceptors, α and β, which roughly corresponds to those in mammals, and that the α type of adrenoceptors mediate the stimulation of PD & SCC, whereas β-adrenoceptors mediate the inhibition. However, based on evidence at hand, no conclusion could be drawn on the subtype of α-adrenoceptors which is involved in the stimulation of sodium transport in the frog skin.

Benzisothiazoles and β-Adrenoceptors: Synthesis and Pharmacological Investigation of Novel Propanolamine and Oxypropanolamine Derivatives in Isolated Rat Tissues

Giovanni Morini,Enzo Poli,Mara Comini,Alessandro Menozzi,Cristina Pozzoli 대한약학회 2005 Archives of Pharmacal Research Vol.28 No.12

In an attempt to examine the ability of benzisothiazole-based drugs to interact with β-adrenoceptors, a series of 1,2-benzisothiazole derivatives, which were substituted with various propanolamine or oxypropanolamine side chains in the 2 or 3 position, were synthesised and tested. The pharmacological activity of these compounds at the β-adrenoceptors was examined using isolated rat atria and small intestinal segments, which preferentially express the β1- and β3-adrenoceptor-mediated responses, respectively. None of these products showed any β- adrenoceptor agonistic activity. In contrast, the 2- and 3-substituted isopropyl, tert-butyl, benzyl, and piperonyl derivatives 2a-d and 3a-d elicited surmountable inhibition of the isoprenaline- induced chronotropic effects in the atria, suggesting competitive antagonism at the β1- recognition site. The pA2 values revealed tert-butyl 3b and the isopropyl substituted piperonyl derivatives 3a to be the most effective. Remarkably, many of the 2-substituted propanolamines were less active than the corresponding 3-substituted oxypropanolamines. With the exception of compound 3b, none of these drugs antagonised the muscle relaxant activity of isoprenaline in the intestine, suggesting no effect on the β3- adrenoceptors. These results confirm the ability of the benzisothiazole ring to interact with the β-adrenoceptors, and demonstrate that 2-substitution with propanolamine or 3-substitution with oxypropanolamine groups yields compounds with preferential antagonistic activity at the cardiac β1-adrenoceptors. The degree of antagonism depends strongly on both the nature of the substituent and its position on the benzisothiazole ring.

가토에서 뇌실내 Calcium Antagonists가 Methoxamine과 Clonidine의 혈압및 심박수 변동에 미치는 영향

김종근(Jong Keun Kim),백영홍(Yung Hong Baik) 대한약리학회 1986 대한약리학잡지 Vol.22 No.2

Urethane 마취 가토에서 뇌내 alpha-1및 alpha-2 adrenoceptor의 작용에 미치는 calcium antagonist의 영항을 알아보고자 뇌실내 methoxamine과 clonidine의 혈압및 심박수 변동에 미치는 diltiazem, nifedipine의 영향을 조사한 결과, 1). 뇌실내 methgramine(1mg)은 혈압상승및 심박수 감소를 일으켰고, 뇌실내 clonidine(30μg)은 혈압하강및 심박수 감소를 일으켰다. 2). 뇌실내 diltiazem과 nifedipine은 dose-dependent한 혈압하강을 일으켰으며 심박수 감소를 일으켰다. Diltiazem에 비하여 nifedipine은 혈압하강 효과는 크고 심박수 감소효과는 작았다. 뇌실내 diltiazem(400μg), nifedipine(35μg)의 혈압하강 작용은 완만하고 지속적이었으나 같은 양의 정맥내 투여효과는 일과성이었다. 3). 뇌실내 diltiazem(400μg)이나 nifedipine(35, 350μg) 처리 후에 methoxamine(1mg)의 혈압상승 효과는 영향받지 않았으나 심박수감소 효과는 유의하게 감약되었다. 4). Clonidine의 혈압하강 작용은 뇌실내 diltiazem(400μg)이나 nifedipine(35, 350μg) 처리 후에 감약되었으나 정맥 내 diltiazem(200μg/kg)이나 nifedipine(30μg/kg) 후에는 영향받지 않았다. Clonidine의 심박수 감소작용은 .뇌실내및 정맥내 diltiazem이나 nifedipine 처리후에 감약되었다. 5). 뇌실내 clonidine(30μg) 처 리후 뇌실내 diltiazem(400μg)과 nifedipine(350μg)의 혈압하강및 심박수 감소효과는 영향 받지 않고 그대로 나타났다. 이상의 결과로 diltiazem과 nifedipine은 가토뇌내에서 methoxamine에 의한 혈압상승의 작용점인 alrfia-1 adrenoceptor의 흥분에는 영향을 미치지 못하나 clonidine의 작용점인 alpha-2 adrenoceptor의 흥분에 의한 혈압하강및 심박수 감소효과는 억제한다고 추론하였다. To delineate the relationship between subtypes of central alpha-adrenoceptor and central calcium channel, influences of intracerebroventricular (icv) diltiazem and nifedipine on the changes of blood pressure and heart rate by icv methoxamine and clonidine were investigated in urethane-anesthetized rabbits. 1) Methoxamine (1mg, icv) produced pressor and bradycardiac effect and clonidine (30μg, icv) produced hypotension and bradycardia. 2) Icv diltiazem and nifedipine elicited dose-dependent deprcssor and bradycardiac responses. The depressor response to nifedipine was more prominent than that to diltiazem but the bradycardiac effect of nifedipine was smaller than that of diltiazem. The depressor responses to icy nifedipine (35μg) and icv diltiazem (400μg) were persistent but those to intravenous (iv) nifedipine (35μg/kg) and diltiazem (200μg/kg) were transient. 3) The pressor response to methoxamine was little affected by pretreatment with in diltiazem (400μg) or icv nifedipine (35, 350μg) but the bradycardiac response to methoxamine was significantly attenuated by the same pretreatment. 4) The depressor response to clonidine was markedly attenuated by pretreatment with icv diltiazem (400μg) or icv nifedipine (35, 350μg) but not affected by pretreatment with iv diltiazem (200μg/kg) or iv nifedipine (20μg/kg). Pretreatment with icv and iv diltiazem or nifedipine reduced the bradycardiac effect of clonidine. 5) Pretreatment with icv clonidine had no effect on the depressor and bradycardiac responses to in diltiazcm or icv nifedipine. These results indicate that diltiazem and nifedipine have no effect on icv methoxamine-induced pressor response elicited by the activation of central alpha-l adrenoceptors whereas the icv clonidine-induccd depressor and bradycardiac effects which result from the activation of central alpha-2 adrenoceptors are inhibited by the calcium antagonists.

Effects of Intracerebroventricular Calcium Antagonists on Changes of Blood Pressure and Heart Rate by Methoxamine and Clonidine in Rabbits

김종근,백영홍,Kim, Jong-Keun,Baik, Yung-Hong The Korean Society of Pharmacology 1986 대한약리학잡지 Vol.22 No.2

Urethane 마취 가토에서 뇌내 alpha-1및 alpha-2 adrenoceptor의 작용에 미치는 calcium antagonist의 영항을 알아보고자 뇌실내 methoxamine과 clonidine의 혈압및 심박수 변동에 미치는 diltiazem, nifedipine의 영향을 조사한 결과, 1). 뇌실내 methgramine(1mg)은 혈압상승및 심박수 감소를 일으켰고, 뇌실내 clonidine$(30{\mu}g)$은 혈압하강및 심박수 감소를 일으켰다. 2). 뇌실내 diltiazem과 nifedipine은 dose-dependent한 혈압하강을 일으켰으며 심박수 감소를 일으켰다. Diltiazem에 비하여 nifedipine은 혈압하강 효과는 크고 심박수 감소효과는 작았다. 뇌실내 diltiazem$(400{\mu}g)$, nifedipine$(35{\mu}g)$의 혈압하강 작용은 완만하고 지속적이었으나 같은 양의 정맥내 투여효과는 일과성이었다. 3). 뇌실내 diltiazem$(400{\mu}g)$이나 nifedipine$(35,\;350{\mu}g)$ 처리 후에 methoxamine(1mg)의 혈압상승 효과는 영향받지 않았으나 심박수감소 효과는 유의하게 감약되었다. 4). Clonidine의 혈압하강 작용은 뇌실내 diltiazem$(400{\mu}g)$이나 nifedipine$(35,\;350{\mu}g)$ 처리 후에 감약되었으나 정맥 내 diltiazem$(200{\mu}g/kg)$이나 nifedipine$(30{\mu}g/kg)$ 후에는 영향받지 않았다. Clonidine의 심박수 감소작용은 .뇌실내및 정맥내 diltiazem이나 nifedipine 처리후에 감약되었다. 5). 뇌실내 clonidine$(30{\mu}g)$ 처 리후 뇌실내 diltiazem$(400{\mu}g)$과 nifedipine$(350{\mu}g)$의 혈압하강및 심박수 감소효과는 영향 받지 않고 그대로 나타났다. 이상의 결과로 diltiazem과 nifedipine은 가토뇌내에서 methoxamine에 의한 혈압상승의 작용점인 alrfia-1 adrenoceptor의 흥분에는 영향을 미치지 못하나 clonidine의 작용점인 alpha-2 adrenoceptor의 흥분에 의한 혈압하강및 심박수 감소효과는 억제한다고 추론하였다. To delineate the relationship between subtypes of central alpha-adrenoceptor and central calcium channel, influences of intracerebroventricular (icv) diltiazem and nifedipine on the changes of blood pressure and heart rate by icv methoxamine and clonidine were investigated in urethane-anesthetized rabbits. 1) Methoxamine (1mg, icv) produced pressor and bradycardiac effect and clonidine $(30\;{\mu}g,\;icv)$ produced hypotension and bradycardia. 2) Icv diltiazem and nifedipine elicited dose-dependent deprcssor and bradycardiac responses. The depressor response to nifedipine was more prominent than that to diltiazem but the bradycardiac effect of nifedipine was smaller than that of diltiazem. The depressor responses to icy nifedipine $(35{\mu}g)$ and icv diltiazem $(400{\mu}g)$ were persistent but those to intravenous (iv) nifedipine $(35{\mu}g/kg)$ and diltiazem $(200{\mu}g/kg)$ were transient. 3) The pressor response to methoxamine was little affected by pretreatment with in diltiazem $(400{\mu}g)$ or icv nifedipine $(35,\;350{\mu}g)$ but the bradycardiac response to methoxamine was significantly attenuated by the same pretreatment. 4) The depressor response to clonidine was markedly attenuated by pretreatment with icv diltiazem $(400{\mu}g)$ or icv nifedipine $(35,\;350{\mu}g)$ but not affected by pretreatment with iv diltiazem $(200{\mu}g/kg)$ or iv nifedipine $(20{\mu}g/kg)$. Pretreatment with icv and iv diltiazem or nifedipine reduced the bradycardiac effect of clonidine. 5) Pretreatment with icv clonidine had no effect on the depressor and bradycardiac responses to in diltiazcm or icv nifedipine. These results indicate that diltiazem and nifedipine have no effect on icv methoxamine-induced pressor response elicited by the activation of central alpha-l adrenoceptors whereas the icv clonidine-induccd depressor and bradycardiac effects which result from the activation of central alpha-2 adrenoceptors are inhibited by the calcium antagonists.

기니픽 심근의 전기생리학적 특성에 미치는 α¹-Adrenoceptor 자극효과

김진상,Kim, Jin-sang 대한수의학회 1993 大韓獸醫學會誌 Vol.33 No.2

The effects of ${\alpha}_1$-adrenergic stimulation on membrane potential, intracellular sodium activity $(a_N{^i{_a}})$, and contractility were investigated in the isolated papillary muscle of euthyroid, hyperthyroid, and hypothyroid guinea pigs. Cardiac alterations in the thyroid state have been shown to induce marked changes in action potential characteristics, the most pronounced shortening of action potential duration by hyperthyroidism and an increase in duration by hypothyroidism. $10^{-5}M$ Phenylephrine produced a decrease in $(a_N{^i{_a}})$ in euthyroid and hypothyroid preparations, but an increase in $(a_N{^i{_a}})$ in hyperthyroid ones. The major findings were that phenylephrine produced a stronger positive inotropic effect(PIE) without initial negative inotropic effect(NIE) in hyperthyroid preparations, while phenylephrine produced markedly NIE in hypothyroid ones. The alterations in membrane potential, $(a_N{^i{_a}})$, and contractility were abolished by $3{\times}10^{-5}M$ prazosin in hypothyroidism. In hypothyroid ventricular muscle, the decrease in $(a_N{^i{_a}})$ caused by phenylephrine were not abolished or reduced by $10^{-5}M$ strophanthidin, $10^{-5}M$ TTX, $3{\times}10^{-4}M$ lidocaine, or $100^{-5}M$ verapamil. These results indicate that the ${\alpha}_1$-adrenoceptor-mediated decrease in $(a_N{^i{_a}})$ is not associated with a stimulation of the $Na^+$-$K^+$ pump, inhibition of the $Na^+$ or $Ca^+$ channel in hypothyroid ventricular muscle. $10^{-5}M$ Phenylephrine decreased $(a_N{^i{_a}})$ but increased $(a_N{^i{_a}})$ in the presence of a PKC activator phorbol dibutyrate$(PDB_u)$. In conclusion, it is suggested that the following sequence of events in response to phenyleplhane occur in guinea pig ventricular muscle. First, changes in thyroid state may contribute to the ventacular electrophysiological propeties or ion transport system. Second, the adrenoceptor-mediated initial transient NIE may be associated with the decrease in $(a_N{^i{_a}})$ by PKC activation.

소(우(牛))의 식도구 평활근 절편에 대한 catecholamine의 작용

조제열,양일석,Cho, Je-yoel,Yang, Il-suk 대한수의학회 1991 大韓獸醫學會誌 Vol.31 No.2

Effects of catecholamines were investigated on isolated strips of the male cattle oesophageal groove. In the circular muscles of the bottom and longitudinal muscles of the lip. isometric tensions was recorded with isometric myograph in 25ml organ bath. The results were as follows: 1. The muscular activity was different in preparations from the two parts. In the longitudinal muscle from the lip, rhythmic contractions generally occurred. while in the circular muscle from the bottom they were not seen almost. 2. In the circular muscle of the bottom, the increased tone and biphasic contractions were caused by catecholamines. And these contractions were mediated through $\alpha$-excitatory adrenoceptor. Also circular muscle showed minor inhibitory response to catecholamines. And these effects were mediated through $\beta$-inhibitory adrenoceptor. But the circular muscle was more sensitive to the $\alpha$-excitatory effect than $\beta$-inhibitory effect. 3. In logitudinal muslce of the lip. rhythmic contractions were reduced or disappeared by catecholamines(especially propranolol) and these effects were mediated through $\beta$-adrenoceptor.

장평활근의 수축성에 대한 amitraz의 영향

신동호,임채미,김재하,Shin, Dong-ho,Lim, Chae-mi,Kim, Jae-ha 대한수의학회 1995 大韓獸醫學會誌 Vol.35 No.2

Amitraz frequently causes the side effect of intestinal stasis or bloat in mammals. It is very similar to the side effect of xylazine or clonidine which produce the inhibition of intestinal motility through the stimulation of ${\alpha}_2$ adrenoceptor. Therefore, we examined whether amitraz causes intestinal stasis or bloat through the inhibition of intestinal motility or whether amitraz produces the inhibition of intestinal motility through the stimulation of ${\alpha}_2$ adrenopceptor. Amitraz inhibited the intestinal motility in a dose-dependent manner in isolated rabbit jejunum and isolated pig ileum. These inhibitory effects of amitraz were blocked by yohimbine but not by prazosin. The effect of intestinal contraction of carbachol or high-potassium was not affected by the pretreatment of amitraz. However, the con-traction of histamine was inhibited by the pretreatment of amitraz. It is concluded that amitraz mainly inhibits the intestinal motility through the stimulation of ${\alpha}_2$-adrenoceptor although partially antihistaminic action of amitraz can be involved.

Involvement of α_1B-adrenoceptors and Rho kinase in contractions of rat aorta and mouse spleen

Hadeel A. Alsufyani,James R. Docherty The Korean Society of Pharmacology 2023 The Korean Journal of Physiology & Pharmacology Vol.27 No.4

α₁-adrenoceptors link via the G-protein Gq/G₁₁ to both Ca²⁺ entry and release from stores, but may also activate Rho kinase, which causes calcium sensitization. This study aimed to identify the subtype(s) of α₁-adrenoceptor involved in Rho kinase-mediated responses in both rat aorta and mouse spleen, tissues in which contractions involve multiple subtypes of α₁-adrenoceptor. Tissues were contracted with cumulative concentrations of noradrenaline (NA) in 0.5 log unit increments, before and in the presence of an antagonist or vehicle. Contractions produced by NA in rat aorta are entirely α₁-adrenoceptor mediated as they are competitively blocked by prazosin. The α_1A-adrenoceptor antagonist RS100329 had low potency in rat aorta. The α_1D-adrenoceptor antagonist BMY7378 antagonized contractions in rat aorta in a biphasic manner: low concentrations blocking α_1D-adrenoceptors and high concentrations blocking α_1B-adrenoceptors. The Rho kinase inhibitor fasudil (10 µM) significantly reduced aortic contractions in terms of maximum response, suggesting inhibition of α_1B-adrenoceptor mediated responses. In the mouse spleen, a tissue in which all 3 subtypes of α₁-adrenoceptor are involved in contractions to NA, fasudil (3 µM) significantly reduced both early and late components to the NA contraction, the early component involving α_1B- and α_1D-adrenoceptors, and the late component involving α_1B- and α_1A-adrenoceptors. This suggests that fasudil inhibits α_1B-adrenoceptor mediated responses. It is concluded that α_1D- and α_1B-adrenoceptors interact in rat aorta and α_1D-, α_1A- and α_1B-adrenoceptors interact in the mouse spleen to produce contractions and these interactions suggest that one of the receptors preferentially activates Rho kinase, most likely the α_1B-adrenoceptor.

The association between polymorphisms of β-adrenoceptors and preeclampsia

Ji Hyae Lim,Shin Young Kim,So Yeon Park,Jae Hyug Yang,Jung Yeol Han,Dal Soo Hong,June Seek Choi,Kyu Hong Choi,Hyun Mee Ryu 대한의학유전학회 2007 대한의학유전학회지 Vol.4 No.2

목적 : 아드레너직 수용체는 약물학적 분류에 의해 β₁-, β₂-, β₃ 아드레너직 수용체로 구분된다. 각 아류형 수용체의 유전자는 수용체의 기능에 영향을 주는 다형성들을 가진다(1 아드레너직 수용체: Ser49Gly, β₂ 아드레너직 수용체: Gln27Glu β₃ 아드레너직 수용체: Trp64Arg). 이번 연구의 목적은 자간전증에서 아드레너직 수용체 아류형 각각의 대립 유전자와 유전자형의 분포를 연구하고, β 아드레너직 수용체들의 조합된 유전자형이 자간전증과 관계가 있는지 조사하는 것이다. 방법 : 한국인 자간전증 임산부 159명과 정상 임산부 168명으로부터 DNA 추출을 위해 혈액 샘플을 수집하였다. 각 아류형 수용체들의 유전자형은 중합효소 연쇄반응과 제한효소 절단 절편의 길이 다양성에 기초한 유전자 검색법을 사용하여 결정하였다. 결과 : β₁과 β₂ 아드레너직 수용체 유전자의 다형성 연구에서, 각 수용체 유전자들의 대립 유전자와 유전자형 분포는 두 군 간에 차이가 없었다. 그러나 β₃ 아드레너직 수용체 유전자의 돌연변이 대립유전자는 정상군보다 자간전증군에서 보다 빈번하게 나타났다(P<0.05, 위험도 1.57, 95% 신뢰구간 1.01-2.46). 더욱이 β₃ 아드레너직 수용체 유전자의 이형접합체는 정상군과 비교했을 때 자간전증군에서 증가하였다(P<0.05, 위험도 1.76, 95% 신뢰구간 1.06-2.92). 아류형 아드레너직 수용체들의 세 가지 다형성들을 조합하여 평가하였을 때, β₁과 β₃ 아드레너직 수용체는 이형접합체이고 β₂ 아드레너직 수용체는 정상 동형접합체로 구성된 특별한 유전자형을 지닌 임산부는 자간전증의 위험이 유의성 있게 증가하였다(P<0.05, 위험도 3.01, 95% 신뢰구간 1.12-8.08). 결론 : 아류형 아드레너직 수용체들의 조합된 유전자형(Ser/Gly, Gln/Gln, Trp/Arg)은 자간전증의 위험과 관계가 있었다. Purpose: The β-adrenoceptors are pharmacologically classified into β₁-, β₂- and β₃-adrenoceptor, The gene of each subtype has polymorphisms related to trier function (β₁-adrenoceptor: Ser49Gly, β₂-adrenoceptor : Gln27Glu, β₃-adrenoceptor: Trp64Arg). The objectives of this study were to analyse the allelic and genotypic distribution of the representative polymorphism of β-adrenoceptors in preeclampsia and to investigate whether combined genotype of β-adrenoceptors may be associated with preeclampsia. Methods : Blood samples were collected from a Korean population (159 preeclamptic pregnancies and 168 normotensive pregnancies). The β₁-, β₂- and β₃-adrenoceptor genotypes was determined using polymerase chain reaction-restriction fragment length polymorphism. Results: There were no differences in allelic and genotypic distribution of β₁- and β₂-adrenoceptor polymorphisms between the two groups. However, the Arg allele of β₃-adrenoceptor polymorphism were more frequent in preecalmpsia than in controls (P<0.05, OR=1.57, 95% Cl=1.01-2.46). Moreover, prevalence of genotype carrying heterozygote of β₃-adrenoceptor polymorphism was increased in preeclampsia compared with controls (p<0,05, OR 1.76, 95 % Cl 1.06-2.92). When combination of the three polymorphisms were evaluated, pregnancies with the particular combined genotype that is consisted of heterozygote of β₁-, β₃-adrenoceptor and wild homozygote of β₂-adrenoceptor (Ser/Gly, Gln/Gln, Trp/Arg), showed a significant increase in the risk of preeclampsia (P<0,05, OR=3,01, 95 % Cl 1.12-8.08). Conclusion: A particular combined genotype (Ser/Gly, Gln/Gln, Trp/Arg) of - adrenoceptors was associated with the risk of preeclampsia.