title: Role of the systemic vasculature in the hemodynamic response to changes in plasma ionized calcium.
abstract: Hemodynamic consequences of sustained (one hour) hypocalcemia and hypercalcemia (plasma ionized calcium concentration [Ca++] maintained approximately 60% below or above normal, encompassing the clinical range) were studied and the influence of beta blockade on these hemodynamic alterations examined in 16 anesthetized, closed-chest dogs. Alterations in [Ca++] were associated with directionally similar changes in mean arterial pressure, whereas on the average cardiac output remained unchanged. Thus, the peripheral vasculature played an important role in the hemodynamic response to alterations in [Ca++]. The state of beta adrenergic activity was an important determinant of the hemodynamic response to hypocalcemia. Prior to beta blockade, hypocalcemia was associated with decreased systemic vascular resistance, whereas after beta blockade with propranolol hydrochloride, systemic vascular resistance was not different from control except at the five-minute observation period, and cardiac output and stroke volume fell.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D006439:Hemodynamics / Q000187:drug effects*; D006934:Hypercalcemia / Q000503:physiopathology*; D006996:Hypocalcemia / Q000503:physiopathology*; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D000319:Adrenergic beta-Antagonists; D002118:Calcium