EFFECT OF PRENATAL HYPOXIA ON CONTRACTILE PERFORMANCE AND RESPONSIVENESS TO CA2-HEART( IN THE ISOLATED PERINATAL RAT)

The effect of prenatal hypoxic stress on the cardiac contractile funct ion and responsiveness to calcium was studied in rats during the perin atal period. Pregnant rats were exposed to intermittent high altitude hypoxia from day 14 to 18 of pregnancy. Foetal hearts (prenatal day 22 ) and the hearts of offsprings (days 1, 4 and 7) were isolated and per fused in the Langendorff mode. Developed force of contraction (DF) as well as the rate of Force development and fall were measured a) at the Ca2+ concentration of 1.25 mmol.l(-1), b) under increasing Ca2+ conce ntration (from 0.6 to 10.0 mmol.l(-1)). Body and heart weights were si gnificantly smaller in hypoxic than in matched control rats starting f rom day 1. The contractile performance of hypoxic hearts did not diffe r from controls. Their inotropic response to increasing Ca2+ concentra tions was, however, significantly reduced on prenatal day 22 and postn atal day 7. Our results suggest that prenatal maternal hypoxia affects the cardiac inotropic responsiveness to Ca2+ even postnatally.