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This Article Full Text Full Text (PDF) All Versions of this Article: 566/1/189    most recent jphysiol.2005.083493v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Morris, J. L Articles by Jobling, P. Search for Related Content PubMed PubMed Citation Articles by Morris, J. L Articles by Jobling, P.

¹ Centre for Neuroscience, Flinders University, Adelaide, SA 5001, Australia

Vasodilatation produced by stimulation of preganglionic neurones in lumbar and sacral pathways to pelvic ganglia was studied using an in vitro preparation of guinea-pig uterine artery and associated nerves in a partitioned bath allowing selective drug application to the ganglia or artery. Arterial diameter was monitored using real time video imaging. Vasodilatations produced by hypogastric nerve stimulation (HN; 300 pulses, 10 Hz) were significantly larger and longer in duration than with pelvic nerve stimulation (N = 18). Stimulation of ipsilateral lumbar splanchnic nerves or ipsilateral third lumbar ventral roots also produced prolonged vasodilatations. Blockade of ganglionic nicotinic receptors (0.1–1 mM hexamethonium) delayed the onset and sometimes reduced the peak amplitude of dilatations, but slow dilatations persisted in 16 of 18 preparations. These dilatations were not reduced further by 3 µM capsaicin applied to the artery and ganglia, or ganglionic application of 1 µM hyoscine, 30–100 µM suramin or 10 µM CNQX. Dilatations were reduced slightly by ganglionic application of NK1 and NK3 receptor antagonists (SR140333, SR142801; 1 µM), but were reduced significantly by bathing the ganglia in 0.5 mM Ca²⁺ and 10 mM Mg²⁺. Intracellular recordings of paracervical ganglion neurones revealed fast excitatory postsynaptic potentials (EPSPs) in all neurones on HN stimulation (300 pulses, 10 Hz), and slow EPSPs (3–12 mV amplitude) in 25 of 37 neurones. Post-stimulus action potential discharge associated with slow EPSPs occurred in 16 of 37 neurones (firing rate 9.4 ± 1.5 Hz). Hexamethonium (0.1–1 mM) abolished fast EPSPs. Hexamethonium and hyoscine (1 µM) did not reduce slow EPSPs and associated post-stimulus firing in identified vasodilator neurones (with VIP immunoreactivity) or non-vasodilator paracervical neurones. These results demonstrate a predominantly sympathetic origin of autonomic pathways producing pelvic vasodilatation in females. Non-cholinergic mediators of slow transmission in pelvic ganglia produce prolonged firing of postganglionic neurones and long-lasting dilatations of the uterine artery. This mechanism would facilitate maintenance of pelvic vasodilatation on stimulation of preganglionic neurones during sexual activity.

(Received 20 January 2005; accepted after revision 29 March 2005; first published online 31 March 2005)
Corresponding author J. L. Morris: Department of Anatomy & Histology, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia. Email: judy.morris{at}flinders.edu.au

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