Neurally evoked responses of rat mesenteric resistance arteries are dependent on intracellular release of calcium.
Rat mesenteric resistance arteries (diameter less than 250 microns) were isolated and mounted in a myograph, and experiments were designed to test whether neurally evoked responses of these vessels are dependent on intracellular release of calcium. The responses to nerve stimulation were completely abolished in calcium-free media, and the possible contribution of intracellular release of calcium could therefore not be examined by switching to a calcium-free solution. Instead, the vessels were stimulated intermittently for 5 s at intervals of 90 s. Following 5 s of nerve stimulation, the intracellular calcium stores were depleted by application of 25 mM caffeine for 15 s. Vessels were then bathed in calcium-free saline, and subsequently 2.5 mM Ca2+ was replaced at varying times prior to nerve stimulation. With 5 s allowed for calcium repletion, the response to nerve stimulation was significantly smaller than the nerve response after 40 s in calcium-containing saline. The results suggest that the response to nerve stimulation is dependent on the time allowed for the intracellular store to refill, implying that intracellular release of calcium is a critical determinant of the neurogenic response in resistance arteries.
Nielsen
H
H
Department of Pharmacology, University of Aarhus, Denmark.
Mulvany
M J
MJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D009420:Nervous System / Q000187:drug effects; D009424:Nervous System Physiological Phenomena; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D002118:Calcium; D011224:Prazosin