AJP - Heart and Circulatory Physiology, Vol 261, Issue 6 1842-H1847, Copyright © 1991 by American Physiological Society

ARTICLES

Regional circulatory contributions to increased systemic vascular conductance of pregnancy

D. Curran-Everett, K. G. Morris Jr and L. G. Moore
Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver 80262.

In pregnancy, maternal systemic vascular conductance increases, a new vascular circuit grows, and the maternal systemic circulation develops a diminished pressor response to angiotensin II (ANG II). However, the quantitative contributions of the latter two circulatory changes to the increased systemic vascular conductance of pregnancy have not been explored. In this experiment, we examined regional circulatory contributions to the increased systemic vascular conductance in conscious, late-gestation guinea pigs. Systemic arterial pressure, cardiac output (dye dilution), and regional blood flows (radiolabeled microspheres) were measured during baseline conditions and progressive ANG II infusion. Systemic and regional conductances were calculated from arterial pressure and cardiac output or regional blood flows. In pregnancy, maternal systemic vascular conductance increased from 3.2 to 5.0 ml.min-1.mmHg-1 (P less than 0.001); increased nonuteroplacental conductance contributed 71% to the increase in whole body conductance. Pregnancy tended to decrease the nonuteroplacental conductance response (P = 0.072), but did not change the uteroplacental conductance response (P greater than or equal to 0.29), to ANG II. The increased uteroplacental blood flow of pregnancy was preserved during ANG II-induced vasoconstriction. We conclude that maternal systemic vascular conductance increased primarily because nonuteroplacental vascular conductance increased.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				A. Y. H. Wong, S. Kulandavelu, K. J. Whiteley, D. Qu, B. L. Langille, and S. L. Adamson Maternal cardiovascular changes during pregnancy and postpartum in mice Am J Physiol Heart Circ Physiol, March 1, 2002; 282(3): H918 - H925. [Abstract] [Full Text] [PDF]

				C. R. Rosenfeld Mechanisms regulating angiotensin II responsiveness by the uteroplacental circulation Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2001; 281(4): R1025 - R1040. [Abstract] [Full Text] [PDF]

				B. E. Cox, C. E. Williams, and C. R. Rosenfeld Angiotensin II indirectly vasoconstricts the ovine uterine circulation Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2000; 278(2): R337 - R344. [Abstract] [Full Text] [PDF]

				M. M. White, R. E. McCullough, R. Dyckes, A. D. Robertson, and L. G. Moore Effects of pregnancy and chronic hypoxia on contractile responsiveness to alpha 1-adrenergic stimulation J Appl Physiol, December 1, 1998; 85(6): 2322 - 2329. [Abstract] [Full Text] [PDF]

				L. Keyes, D. M. Rodman, D. Curran-Everett, K. Morris, and L. G. Moore Effect of K+ATP channel inhibition on total and regional vascular resistance in guinea pig pregnancy Am J Physiol Heart Circ Physiol, August 1, 1998; 275(2): H680 - H688. [Abstract] [Full Text] [PDF]

				A. Poppas, S. G. Shroff, C. E. Korcarz, J. U. Hibbard, D. S. Berger, M. D. Lindheimer, and R. M. Lang Serial Assessment of the Cardiovascular System in Normal Pregnancy: Role of Arterial Compliance and Pulsatile Arterial Load Circulation, May 20, 1997; 95(10): 2407 - 2415. [Abstract] [Full Text]