Fetal alcohol effects on the postnatal development of the rat myocardium: an ultrastructural and morphometric analysis.

Heart disease is an entity frequently seen in the fetal alcohol syndrome. This paper describes the effect of in utero ethanol exposure on the postnatal ultrastructural development of rat cardiac muscle. To determine this time-pregnant Sprague-Dawley rats were fed either a nutritionally balanced protein- and vitamin-enriched liquid ethanol diet (with 36% of the calories derived from ethanol) or a liquid diet with maltose-dextrins isocalorically substituted for ethanol. The latter group was designated the pairfed control group. At birth, pups of both the groups were surrogate-fostered by normal dams. Body weights and crown-rump lengths were significantly less in the rat pups exposed to ethanol in utero at 21 days postnatal. Ultrastructural analysis of the cardiac muscle was performed at 7, 14, and 21 days postnatal in ethanol and pairfed groups. Several morphological features of myocyte damage were observed in ethanol-exposed pups, predominantly at 7 days postnatal, with nearly total absence of myocyte damage by 21 days postnatal. The most outstanding changes were observed in the myofibrils, which showed dysplastic changes at 7 days postnatal, a delay in M-band structural development at 14 days postnatal, and a significantly smaller myofibril volume density per tissue volume at 21 days postnatal in the ethanol rat pups compared to the pairfed controls.