Effect of cardiac glycosides on the coronaries: physiologic and morphologic studies in the dog heart.
The effect of K- strophanthoside on coronary blood flow (CBF) was studied in open chest dogs anaesthetized with pentobarbital sodium. K- strophanthoside (3.5 and 7.0 X 10(-8) mol X kg-1 i.v.) elicited a dose-dependent decrease of CBF and an increase of late diastolic coronary resistance. Intracoronary injections of the drug (1.2 X 10(-8) mol) produced selective coronary constriction. The haemodynamic pattern indicated a direct vasoconstrictor effect, independent of the extracoronary (cardiotonic) action of the drug. In the polarization microscope Romh  anyi 's aldehyde bisulphite-toluidine blue (ABT) reaction as adapted for the detection of cardiac glycosides showed profuse binding of strophanthoside to the coronary vessel wall. K- strophanthoside significantly reduced the CBF increase elicited by adenosine infusion (2 X 10(-7) mol X kg-1) into the left heart. Verapamil (4 X 10(-7) mol X kg-1, i.v.), on the other hand, counteracted the strophanthoside action on CBF. The results suggest that restricted intracellular availability of Ca2+, a prerequisite of physiologic CBF increase, is opposed by cardiac glycosides.
D000241:Adenosine / Q000037:antagonists & inhibitors; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects*; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects*; D007269:Injections, Intra-Arterial; D007275:Injections, Intravenous; D013268:Stimulation, Chemical; D013328:Strophanthins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology
D013328:Strophanthins; C008240:K-strophanthoside; D014700:Verapamil; D000241:Adenosine