Document Detail


Regional differences in sympathetic neurotransmission to cutaneous arteries in the guinea-pig isolated ear.
MedLine Citation:
PMID:  9862386     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effects of sympathetic nerve stimulation on different cutaneous arteries were examined in arteries isolated from guinea-pig ears, by measuring membrane potential changes in smooth muscle cells in response to electrical field stimulation. Resting membrane potential (RMP) was similar in proximal (main ear artery) and distal (3rd or 4th branch order) cutaneous arteries (mean -71 mV). Single stimuli evoked excitatory junction potentials (EJPs) in all arteries. The EJPs in proximal arteries were twice the amplitude, and the time constant of EJP decay was almost half the value, compared with distal cutaneous arteries. EJP amplitude was reduced by > 90% by suramin (30 microM) or alpha,beta,methylene-ATP (alpha,beta,m-ATP)(1 microM) in all proximal, and most distal arteries. Residual responses in distal arteries were resistant to tetrodotoxin. The N-type calcium channel blocker, omega-conotoxin GVIA (30 nM), reduced EJP amplitude by 70-100% in both proximal and distal arteries. Successive EJPs evoked by trains of stimuli at 1 to 5 Hz were depressed in amplitude in proximal arteries, but showed facilitation in distal arteries. EJP depression in proximal arteries was reversed to facilitation by the alpha2-adrenoceptor antagonist, yohimbine (30 nM). Trains of stimuli delivered at 10-20 Hz produced summation of EJPs and active membrane responses in 30% of proximal arteries. Active responses were never detected in distal arteries. Slow depolarizations following the EJPs were detected in most arteries after trains of stimuli, and were abolished by prazosin (0.3 microM) or omega-conotoxin GVIA (30 nM). The density of the perivascular plexus of axons innervating proximal arteries, demonstrated with catecholamine fluorescence histochemistry, was twice that in distal cutaneous arteries. These regional differences in sympathetic neurotransmission suggest that cutaneous vasoconstriction in response to thermoregulatory stimuli, which occurs predominantly in distal cutaneous segments, is likely to be qualitatively different from cutaneous vasoconstriction of proximal arteries in response to other physiological stimuli.
Authors:
J L Morris; T C Cunnane; G D Hirst
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the autonomic nervous system     Volume:  73     ISSN:  0165-1838     ISO Abbreviation:  J. Auton. Nerv. Syst.     Publication Date:  1998 Nov 
Date Detail:
Created Date:  1999-02-25     Completed Date:  1999-02-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8003419     Medline TA:  J Auton Nerv Syst     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  115-24     Citation Subset:  IM    
Affiliation:
Department of Anatomy and Histology, Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia. judy.morris@flinders.edu.au.
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MeSH Terms
Descriptor/Qualifier:
Adrenergic alpha-Antagonists / pharmacology
Animals
Arteries / physiology
Calcium Channel Blockers / pharmacology
Calcium Channels / physiology
Ear
Female
Guinea Pigs
Male
Membrane Potentials / drug effects,  physiology
Peptides / pharmacology
Receptors, Adrenergic, alpha / physiology
Receptors, Purinergic / physiology
Skin / blood supply*,  innervation*
Sympathetic Nervous System / chemistry,  physiology*
Synaptic Transmission / physiology*
Vasoconstriction / drug effects,  physiology
Yohimbine / pharmacology
omega-Conotoxin GVIA
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Calcium Channel Blockers; 0/Calcium Channels; 0/Peptides; 0/Receptors, Adrenergic, alpha; 0/Receptors, Purinergic; 146-48-5/Yohimbine; 92078-76-7/omega-Conotoxin GVIA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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