モルモット摘出精管におけるカテコールアミンの遊離機序,とくにアセチルコリンの役割
スポンサーリンク
概要
- 論文の詳細を見る
The mechanism of catecholamine (CA) release evoked by transmural stumulation (TS) and action of some CA release inhibitors were studied. Isotonic contraction was used as an indicator of CA release. Results: 1) Contractions of TS, exogenous ACh and exogenous noradrenaline were respectively compared as regards influence of various drugs (Tables 1 and 2). 2) The following has been concluded: (1) Contraction of TS is due to stimulation of the hypogastric nerve (sympathetic nerve) ending, resulting in CA release from adrenergic fiber (AF) and ACh release from cholinergic fiber (CF) in this nerve. CA and ACh are related to the TS contraction in a ratio of approx. 6:4. (2) Intervention of ACh as proposed by Burn et al. is not indispensable for the CA release from AF under the influence of TS, however, endogenous ACh released from CF accelerates CA release. (3) Hexamethonium inhibits CA release of exogenous ACh, but not that of TS (and consequently that of endogenous ACh), while pempidine and mecamylamine inhibits both. (4) Bretylium inhibits irreversibly the release of both CA and ACh produced by TS, while inhibiting CA release of exogenous ACh less strongly and reversibly. 3) Against the TS contraction abolished by bretylium after washout, incubation with CA or ACh (followed. by washout) showed a temporary recovery, while that with calcium (followed by washout) resulted in a lasting recovery. Incubation with CA, ACh and calcium respectively restores the release of CA, of ACh and of both. It is suggested that bretylium blocks both AF and CF by competitive inhibition against the transmitters releasing action of calcium.