Different sensitivities to alpha1 adrenoceptor blockade on periarterial sympathetic nerve-induced constriction by low and high frequencies in canine isolated splenic arteries.
The periarterial nerve electrical stimulation at 4 and 10 Hz induced a monophasic vasoconstriction of the canine splenic artery in a pulse number-related manner (1-30 pulses). The responses at 4 Hz were not significantly affected by 0.1 microM prazosin, but abolished by 1 microM alpha, beta-methylene ATP. Prazosin (0.1 microM) partially but significantly inhibited responses at 10 Hz, and the remaining responses were blocked by 1 microM alpha, beta-methylene ATP. It indicates that the monophasic vasoconstrictor response to short pulses of stimulation at a low frequency is mediated by P2X-receptors, whereas the response at a high frequency may be due to activation of not only P2X-receptors but also alpha1 adrenoceptors.
Yang
Xiao-Ping
XP
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
Chiba
Shigetoshi
S
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology*; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism*; D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058469:Receptors, Purinergic P2X; D013157:Splenic Artery / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D011224:Prazosin