Galanin potentiates electrical stimulation and exogenous norepinephrine-induced contractions in the rat vas deferens.

摘要: Abstract In order to evaluate the mode of action galanin (GAL) on neuroeffector mechanism peripheral sympathetic nerve fibers, effects this peptide were tested electrical stimulated and unstimulated preparations isolated rat vas deferens in presence 10−7 M atropine. The contractile responses, which mediated predominantly by activation postganglionic noradrenergic fibers dose-dependently potentiated GAL concentrations ranging from 1 50 nM. facilitatory induced high (> 10 nM) usually returned control level at 2–3 min tachyphylactic. potentiating was not modified pretreatment with propranolol. Contractions produced exogenous norepinephrine (NE) affected low ( GAL, recovered 15 after constant flow washout. developed 5-hydroxytryptamine affected, or slightly inhibited, (1–50 nM). some without stimulation, caused a slight contraction, blocked 10−6 phentolamine tetrodotoxin. These results suggest that receptors exist presynaptically stimulation potentiates release NE terminals during stimulation. Other mechanisms for action, such as influence neuronal uptake catecholamine metabolism, cannot be ruled out.