title: Contractile responses of isolated canine blood vessels to ATP and ADP.
abstract: Effects of ATP and ADP on helically cut strips of canine different blood vessels were studied, in comparison with those of K+ and norepinephrine (N.E.). ATP and ADP were equally effective in causing transient contractions in contrast to sustained contractions induced by K+ and N.E.. The mesenteric, renal arteries and portal veins were sensitive to both nucleotides. The response to the nucleotides was K+ was more dependent on Ca++ and Mg++ concentrations in bathing media than that to N.E.. Treatment of the strips with EGTA in Ca++ -free media quickly abolished the contractile responses to ATP, ADP and K+. Application of 0.1 mM Cd++ attenuated the contractile responses to K+ more markedly than those to N.E., but did not affect ATP action. Verapamil at 0.5 micron inhibited the K+-induced contraction alone, and 2 mM procaine inhibited the response to N.E. alone, but rather intensified the ATP-induced contraction. It may be concluded that ATP and ADP produce a transient contraction of isolated canine blood vessels by a mechanism relating to an increased mobilization of loosely bound Ca++ in cell membranes.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001808:Blood Vessels / Q000187:drug effects*; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D004285:Dogs; D004357:Drug Synergism; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011188:Potassium / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011343:Procaine / Q000494:pharmacology; D014662:Vasoconstrictor Agents; D014700:Verapamil / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D002104:Cadmium; D011343:Procaine; D004533:Egtazic Acid; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D014700:Verapamil; D008274:Magnesium; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine