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  • Title: Sympathetic modulation of cholinergic transmission in cat vesical ganglia is mediated by alpha 1- and alpha 2-adrenoceptors.
    Author: Keast JR, Kawatani M, De Groat WC.
    Journal: Am J Physiol; 1990 Jan; 258(1 Pt 2):R44-50. PubMed ID: 1967915.
    Abstract:
    Modulation of transmission in cat vesical ganglia by exogenous catecholamines or short periods of hypogastric nerve stimulation (HGS) was examined in vivo. HGS (30 Hz, 30 V, 10- to 20-s train) initially caused inhibition of ganglionic transmission, followed by a period of facilitation. The inhibition could be evoked by lower stimulus intensities than the facilitation. The biphasic effect was mimicked by norepinephrine (2-10 micrograms) injected into the inferior mesenteric artery, whereas phenylephrine (5-10 micrograms) usually caused only facilitation. The administration of specific adrenoceptor antagonists showed that the inhibitory responses were mediated by alpha 2-receptors and the facilitatory responses by alpha 1-receptors. The effects of HGS and norepinephrine were also tested on pelvic nerve-evoked bladder contractions. Both caused a brief reduction in contraction amplitude which, for the HGS effect, was mediated mainly by alpha 2-receptors. Noradrenergic inhibition of bladder contractions was mediated by both alpha 2- and beta-adrenoceptors. These studies have shown that sympathetic modulation of ganglionic transmission in the bladder can be either inhibitory or facilitatory, each mediated by a specific receptor type. These two actions may be important during different stages of bladder storage or voiding.
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