Systemic and renal hemodynamic consequences of manipulation of serum calcium and/or parathyroid hormone in the intact conscious mongrel dog.

Studies were undertaken in conscious mongrel dogs to separate the systemic and renal hemodynamic effects of alterations in serum calcium (Ca) from those of parathyroid hormone (PTH) in an intact conscious animal. Blood pressure was measured intra-arterially, cardiac output was determined by dye-dilution or thermodilution, total peripheral resistance (TPR) was calculated from standard formulae, and renal hemodynamics were estimated by the clearance of inulin and para-aminohippurate. Measurements were made before and after a 2 hour calcium chloride (CaCl2) infusion in 10 dogs (group 1). These animals had previously received a dose of PTH to prevent suppression of PTH during the CaCl2 infusion. Ionized calcium (Ca++) and TPR increased significantly. Blood pressure increased but not significantly. Administration of EDTA did not significantly change any systemic hemodynamic variable in eight thyroparathyroidectomized dogs (group 2). Chelation in seven dogs with intact parathyroid glands (group 3) reduced mean ...