title: Cardiovascular effects of acute changes in extracellular ionized calcium concentration induced by citrate and CaCl2 infusions in conscious, chronically instrumented dogs and their interactions with ganglionic blockade.
abstract: To assess the hemodynamic effects of acute changes in extracellular ionized calcium concentration, [Ca2+], seven dogs were chronically instrumented to measure heart rate, aortic, left atrial, and left ventricular (LV) pressures, cardiac output, and coronary and renal blood flows. [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. This protocol was performed in the conscious dogs with and without ganglionic blockade (chlorisondamine 2 mg.kg-1). LV dP/dtmax decreased at low [Ca2+] and increased at high [Ca2+] during all conditions. The other hemodynamic variables measured were only slightly changed by changing [Ca2+] without ganglionic blockade and surprisingly even less with ganglionic blockade. Therefore, the lesser hemodynamic effects induced by acute changes in [Ca2+] in the conscious compared with anesthetized dogs cannot be explained by the depressant effects of the anesthetics upon the autonomic nervous system. We have suggested that the binding of Mg2+ to citrate may be of importance for the minor hemodynamic effects in the conscious dogs.
authors.affiliation: Department of Anesthesiology, University of Texas Medical School, Houston.
authors.forename: E S
authors.initials: ES
authors.lastname: Hysing
authors.forename: J E
authors.initials: JE
authors.lastname: Chelly
authors.forename: M F
authors.initials: MF
authors.lastname: Doursout
authors.forename: R G
authors.initials: RG
authors.lastname: Merin
mesh_terms: D000818:Animals; D001775:Blood Circulation / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D001808:Blood Vessels / Q000187:drug effects; D002118:Calcium / Q000032:analysis*; D002122:Calcium Chloride / Q000494:pharmacology*; D002714:Chlorisondamine / Q000494:pharmacology*; D002951:Citrates / Q000494:pharmacology*; D019343:Citric Acid; D004285:Dogs; D005110:Extracellular Space / Q000737:chemistry*; D005725:Ganglia, Autonomic / Q000187:drug effects; D006321:Heart / Q000187:drug effects* / Q000294:innervation; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D002951:Citrates; D019343:Citric Acid; D002714:Chlorisondamine; D002122:Calcium Chloride; D002118:Calcium