alpha-endorphin and Bradycardia

An intravenous bolus injection of 0.1 ml alpha-endorphin (1 x 10(-8)-1 x 10(-4) g/ml) didn't change the heart rate in frogs. The parasympathetic bradycardia induced by the peripheral vagus stimulation was decreased by alpha-endorphin. This vago-inhibitory action was dose-dependent (1 x 10(-5)-1 x 10(-4) g/ml). The maximal inhibitory action was watched in 4-8 and 9-15 minutes after bolus injection of alpha-endorphin in concentration of 1 x 10(-5) and 1 x 10(-4) g/ml accordingly.

Topics: alpha-Endorphin; Animals; Bradycardia; Dose-Response Relationship, Drug; Electric Stimulation; Electrocardiography; Endorphins; Neural Inhibition; Parasympathetic Nervous System; Ranidae; Time Factors; Vagus Nerve