Pharmacological properties of the adrenergic receptors regulating systemic vascular resistance in the rainbow trout

摘要: 1. The adrenergic receptors in the systemic vasculature of rainbow trout have been pharmacologically characterized using an isolated trunk preparation perfused at constant flow. 2. The dominant α-constrictory are similar to those mammals their adrenaline/noradrenaline potency ratio (3.2/1.0), and natures blockade by phenoxybenzamine yohimbine. However they more selective than mammalian α-receptors, responding directly only adrenaline noradrenaline, not phenylephrine, methoxamine, dopamine, or isoprenaline. 3. Tyramine dopamine cause weak α-adrenergic constriction, apparently indirectly through release catecholamine stores. 4. The response is susceptible inhibition competitive β-blocking agents, but this effect due non-competitive antagonism with a point action beyond receptor. 5. β-dilatory β2, as homologous mammals, also occur, dilatory actions cn be demonstrated against background vasoconstriction. 6. The racemate d,l-isoprenaline potent vasodilator pure isomer l-isoprenaline during tone because α-blocking activity d-isomer.