title: Hemodynamic interactions when combining verapamil, acute changes in extracellular ionized calcium concentration and enflurane, halothane or isoflurane in chronically instrumented dogs.
abstract: To assess the hemodynamic interactions when combining verapamil, acute changes in extracellular ionized calcium concentration [Ca2+] and enflurane (2.5%), halothane (1.2%) or isoflurane (1.6%), seven dogs were chronically instrumented to measure heart rate (HR), aortic, left atrial and left ventricular (LV) pressures, and cardiac output (CO). [Ca2+] was lowered 0.35 mmol.l-1 by citrate infusion and then increased 0.35 mmol.l-1 above control level by CaCl2 infusions. Verapamil was infused at 3 micrograms.kg-1 x min-1 (loading dose 200 (awake), 150 (isoflurane) or 100 (enflurane and halothane) micrograms.kg-1), giving mean verapamil concentrations around 75 (range of means: 66-84 ng.ml-1). Verapamil produced mostly minor changes in the cardiovascular effects of changing [Ca2+] in both awake and anesthetized dogs, indicating mostly additive effects. Verapamil induced a decrease in HR at high [Ca2+] and abolished an increase in mean aortic pressure at both low and high [Ca2+] awake. Verapamil exaggerated the decrease in CO and stroke volume (SV) induced by low [Ca2+] during enflurane anesthesia and abolished the increase in CO induced by low [Ca2+] and exaggerated the increase in SV and LV dP/dtmax induced by high [Ca2+] during halothane anesthesia.
authors: Department of Anesthesiology, University of Texas Medical School, Houston.
authors: E S
authors: ES
authors: Hysing
authors: J E
authors: JE
authors: Chelly
authors: L
authors: L
authors: Jacobson
authors: M F
authors: MF
authors: Doursout
authors: R G
authors: RG
authors: Merin
mesh_terms: D000769:Anesthesia, Inhalation; D000818:Animals; D016279:Atrial Function, Left / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006328:Cardiac Catheterization; D002302:Cardiac Output / Q000187:drug effects; D003243:Consciousness; D004285:Dogs; D004737:Enflurane / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006221:Halothane / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007530:Isoflurane / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects; D014700:Verapamil / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*
chemical_list: D004737:Enflurane; D014700:Verapamil; D007530:Isoflurane; D002118:Calcium; D006221:Halothane