Left ventricular size, output, and structure during guinea pig pregnancy

Abstract

We investigated left ventricular (LV) hemodynamics, pressure-volume relations, and morphometry to determine what cardiac changes characterize pregnancy in the guinea pig. Time-bred virgin guinea pigs were paired by weight with unbred controls. Hemodynamic studies and LV pressure-volume relations were obtained on days 59-68 of the 68-day gestation. Weight of control sows increased from 817 to 902 g (P less than 0.01) and pregnant sows from 810 to 1,251 g (P less than 0.01). LV weights were not different. When indexed for maternal weight minus uterus and contents, pregnancy produced increases in O2 consumption, +48% (P less than 0.01); cardiac output, +32% (P less than 0.05); and stroke volume, +46% (P less than 0.025). Passive LV pressure-volume curves (dP/dV) were shifted to the right (P less than 0.025), but dP/dV at constant pressure was unchanged. Using a thin-walled spherical model, elastic modulus at constant stress was not different. The percent LV inter- and intracellular volumes and myocyte myofibril and organelle volumes were unchanged during pregnancy. In the guinea pig, pregnancy increases LV output, stroke volume, and size without changes in LV mass, morphometry, or elastic modulus.

Gestational diabetes affects platelet behaviour through modified oxidative radical metabolism

“…Pregnancy causes an increase in NO‐dependent relaxation responses to acetylcholine in the human uterine artery [16]. This functional feature is associated with an up‐regulation of endothelial NOS protein expression with enhanced Ca 2+ ‐dependent NOS activity [17] and is consistent with the decreased systemic vascular resistance observed during pregnancy [18]. In agreement with these observations, we found a significant increase in NOS activity in platelets from healthy pregnant women compared with non‐pregnant subjects.…”

Right ventricular systolic pressure load alters myocyte maturation in fetal sheep

“…Hearts were prepared for morphometric analyses as in our previous studies in fetal sheep and in pregnant guinea pigs (11,16), with minor modifications as suggested by other researchers (6,8,19). The heart was removed from the chest, cooled, trimmed, measured, and weighed.…”

Maternal Heart Rate and Stroke Volume in the Pygmy Goat: Effects of Exercise and Cardiac Autonomic Blockade

“…The lack of change of stroke volume with ,?-adrenergic blockade during pregnancy both at rest and during exercise strongly suggests that the adrenergic system does not mediate the increased stroke volume of pregnancy. Cardiac enlargement, inferred from human echocardiographic studies (Katz, Karliner & Resnick, 1978) and measured directly in guinea-pigs (Morton, Tsang, Hohimer, Ross, Thornburg, Faber & Metcalfe, 1984), appears to be the predominant mechanism for increased maternal stroke volume. In spite of the post-exercise fall in stroke volume, cardiac output was maintained by a delay in the recovery of heart rate to resting levels.…”