Amenta F, Collier W L, Erdö S L, Giuliani S, Maggi C A, Meli A
Dipartimento di Scienze Neurologiche, Università La Sapienza, Roma, Italy.
Pharmacology. 1988;37(6):394-402. doi: 10.1159/000138494.
The occurrence and distribution of specific 3H-muscimol binding sites, most probably identical with A type gamma-aminobutyric acid (GABA) receptors, were studied in sections of the rat adrenal gland by light microscope autoradiography. Specific binding was found primarily in the adrenal medulla, in association with chromaffin cells. A limited number of binding sites was also observed within the adrenal cortex. In urethane-anaesthetized hexamethonium-pretreated rats, intravenous GABA produced a set of 'excitatory' cardiovascular effects (increase in heart rate, force of contraction and blood pressure) which were mimicked by intravenous muscimol but not by intravenous baclofen, and were antagonized by pretreatment with bicuculline. The cardiovascular excitatory effects of intravenous GABA were unaffected by reserpine pretreatment, markedly reduced by administration of phentolamine plus propranolol, and almost completely abolished by adrenalectomy. Our findings indicate the presence of GABA receptor sites on adrenal chromaffin cells, whose excitation can produce changes in cardiovascular function.
利用光学显微镜放射自显影技术，在大鼠肾上腺切片中研究了特异性3H - 蝇蕈醇结合位点（极有可能与A型γ-氨基丁酸（GABA）受体相同）的出现情况和分布。特异性结合主要见于肾上腺髓质，与嗜铬细胞相关。在肾上腺皮质内也观察到数量有限的结合位点。在经氨基甲酸乙酯麻醉并预先用六甲铵处理的大鼠中，静脉注射GABA会产生一系列“兴奋性”心血管效应（心率、收缩力和血压升高），静脉注射蝇蕈醇可模拟这些效应，但静脉注射巴氯芬则不能，并且这些效应可被预先用荷包牡丹碱处理所拮抗。静脉注射GABA的心血管兴奋效应不受利血平预处理的影响，酚妥拉明加普萘洛尔给药可使其明显减弱，而肾上腺切除几乎可将其完全消除。我们的研究结果表明，肾上腺嗜铬细胞上存在GABA受体位点，其兴奋可引起心血管功能的变化。
