Independence of connexin expression and vasomotor conduction from sympathetic innervation in hamster feed arteries.
OBJECTIVE
Vasomotor responses can travel along the wall of resistance microvessels by two distinct mechanisms: cell-to-cell conduction through gap junctions or the release of neurotransmitter along perivascular nerves. It is unknown whether vascular innervation influences the expression of connexin molecules which comprise gap junctions, or the conduction of vasomotor responses. In feed arteries of the hamster retractor muscle (RFA), the authors tested whether sympathetic denervation would alter the expression of connexin isoforms and the conduction of vasomotor responses.


METHODS
Using intact vessels with sympathetic innervation and those 7-8 days following denervation surgery, mRNA expression was quantified using real-time PCR, cellular localization of Cx protein was characterized using immunohistochemistry, and vasomotor responses to dilator and constrictor stimuli were evaluated in isolated pressurized RFA.


RESULTS
Connexin protein localization and mRNA expression were similar between innervated and denervated vessels. mRNA levels were Cx43 = Cx37 > Cx45 >> Cx40. Vasodilation to acetylcholine conducted >/=2000 microm along innervated and denervated vessels, as did the biphasic conduction of vasoconstriction and vasodilation in response to KCl. Vasoconstriction to phenylephrine conducted <500 microm and was attenuated (p <.05) in denervated vessels.


CONCLUSIONS
The profile of connexin expression and the conduction of vasomotor responses are largely independent of sympathetic innervation in feed arteries of the hamster retractor muscle (RFA).
The John B. Piercy Laboratory, New Haven, Connecticut 06519, USA.
Robin C
RC
Looft-Wilson
Sara J
SJ
Haug
P Darrell
PD
Neufer
Steven S
SS
Segal
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000294:innervation*; D018031:Connexin 43; D017630:Connexins / Q000032:analysis / Q000235:genetics*; D006224:Cricetinae; D009131:Muscle, Smooth, Vascular / Q000294:innervation; D009132:Muscles / Q000098:blood supply; D009431:Neural Conduction; D012333:RNA, Messenger / Q000032:analysis; D013564:Sympathetic Nervous System; D014661:Vasoconstriction; D014664:Vasodilation; D014666:Vasomotor System / Q000502:physiology*; D000097003:Gap Junction alpha-5 Protein; D000097006:Gap Junction alpha-4 Protein
D000109:Acetylcholine; D018031:Connexin 43; D017630:Connexins; D012333:RNA, Messenger; D000097003:Gap Junction alpha-5 Protein; D000097006:Gap Junction alpha-4 Protein; C082920:connexin 45