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.
Department of Experimental Pharmacology, Bulgarian Academy of Sciences, Sofia.
V N
VN
Mutafova-Yambolieva
R G
RG
Radomirov
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