Maternal involvement in the development of cardiovascular phenotype.

Over the past 20 years, laboratory studies of genetically defined animal models of human essential hypertension have provided valuable information on the pathophysiology of this disturbance in cardiovascular regulation. Relatively fewer studies have examined the impact of preweaning factors on the developing cardiovascular system of hypertensive animals. In our laboratory studies, we have utilized two inbred genetically hypertensive models: the spontaneously hypertensive (SHR) rat and its Wistar/Kyoto (WKY) normotensive control strain as well as the Dahl hypertension-sensitive (SS/Jr) and hypertension-resistant (SR/Jr) strains. To manipulate the preweaning maternal environment, we have employed the technique of reciprocal cross-fostering of litters between hypertensive and matched normotensive mothers. Our findings to date point to the maternal environment as a powerful influence on the development of high blood pressure in genetically hypertensive rats. In general, hypertensive rats reared by normotensive foster mothers have significant reductions in arterial blood pressure in adulthood. Thus, the progression of hypertensive disease is not strictly predetermined by genotypic factors. Rather, a genetic predisposition to hypertension interacts with preweaning environmental factors to determine an animal's cardiovascular phenotype in adulthood.