Chronotropic effects of the reversed carboxyl (RC) analogue of acetylcholine (beta-homobetaine methylester) at defined intraluminal pressures on isolated right rabbit atria.
With continuous perfusion at transmural pressures of 0.1 and 0.5 kPa, beta-homobetaine methylester (HBM) decreased the rate of spontaneously beating atria significantly with an ED50 of about 5 X 10(-6) mol/l. The dose-dependent decrease in the atrial rate was stronger at an intraluminal pressure of 0.5 kPa, at this pressure the dose-response curve sloped more steeply. The stretch acceleration of the atrial rate was also significantly inhibited by HBM. In comparison with acetylcholine, the HBM was over 10 times more effective. Atropine blocked the interactions of the HBM with the muscarinic cholinergic receptors of the pacemaker cells.
D000109:Acetylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects*; D006325:Heart Atria / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D010477:Perfusion; D011817:Rabbits; D013997:Time Factors
C045425:beta-homobetaine methyl ester; D001285:Atropine; D000109:Acetylcholine