Modulatory effects of endothelin-1 on purinergic and adrenergic components of sympathetically-mediated contractile activity of rabbit saphenous artery.
1. The present study has been performed to evaluate the modulatory effects of endothelin-1 (ET-1) on the purinergic and adrenergic components of sympathetically-mediated contractile responses of endothelium-free rabbit saphenous artery preparations. 2. ET-1 increased the smooth muscle tone, the pD2 value being 7.77 +/- 0.05. 3. Postjunctionally, ET-1 enhanced the responses to exogenous adenosine 5'-triphosphate (ATP) and did not influence those to exogenous noradrenaline (NA). 4. ET-1 increased the contractile responses to short-lasting and to long-lasting electrical field stimulation at a frequency of 5 or 10 Hz, showing a tendency towards decreasing the prazosin-sensitive component and increasing the mATP-sensitive component of the contractile responses. 5. In prazosin-treated preparations ET-1 increased the residual mATP-sensitive responses and this effect was more pronounced after yohimbine. 6. In mATP-treated preparations ET-1 increased the residual electrically-induced contractions and this increase was abolished after yohimbine. 7. It is suggested that ET-1 modulates co-transmission in the rabbit saphenous artery by potentiating postjunctionally the purinergic component of the contractile responses to both exogenous ATP or electrical stimulation.
Mutafova-Yambolieva
V N
VN
Department of Experimental Pharmacology, Bulgarian Academy of Sciences, Sofia.
Radomirov
R G
RG
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D004558:Electric Stimulation; D016232:Endothelins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects*
D016232:Endothelins; D000255:Adenosine Triphosphate; D009638:Norepinephrine; D011224:Prazosin