AUTONOMIC NERVOUS INFLUENCE OF THE FEMALE GUINEA-PIG URINARY-BLADDER DURING THE ESTRUS CYCLE

The mammalian urinary bladder receives dual innervation. The excitator y innervation is considered to be partly cholinergic and partly mediat ed via NANC-receptors. Several (co-)transmitters have been suggested. The adrenergic inhibitory innervation is mediated via alpha- and beta- receptors. Female sex hormones could change autonomic influence of uro genital organs. It was considered to be of interest to characterize th e spontaneous and nerve stimulation-induced muscular activity in the u rinary bladder of the female guinea-pig during the oestrus cycle. Both the spontaneous activity and nerve-induced activity varied according to the hormonal status of the animal. An a-adrenergic inhibitory influ ence was identified. It was further confirmed that the excitatory inne rvation could not be blocked by the cholinergic antagonist scopolamine , while alpha-beta-methylene ATP partly inhibited nerve stimulation-in duced smooth muscle response, most prominent at cycle day 6. Indometha cin did not impair spontaneous activity or nerve stimulation-induced a ctivity. Nitric oxide reduced nerve stimulation-induced responses on c ycle day 12. Imperative urinary bladder contractions are reported to d iminish after oestrogen use and in the female a hormonal effect of the nervous influence on the urinary bladder smooth muscle is suggested.