WHY DO METABOLIC RISK FACTORS CLUSTER WITH HYPERTENSION?

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DESCRIPTION: (Adapted from the application) Insulin resistance has been frequently observed in patients with essential hypertension, although the mechanisms responsible for the hypertension "metabolic syndrome" and clustering of cardiovascular risk factors remain poorly understood. Evidence from both family studies and experimental animals indicates that genetic risk factors may play a significant role in the clustering of cardiovascular risk factors. The spontaneously hypertensive rat (SHR), a widely studied experimental animal model of human essential hypertension, also demonstrates increased plasma insulin levels and insulin resistance when compared with other strains with low blood pressure. The PI and her collaborators have derived a novel SHR congenic strain that provides an opportunity to investigate the clustering of hypertension and insulin resistance. By transferring a piece of chromosome 4 from the normotensive Brown Norway rat onto the genetic background of the SHR rat, the applicant has bracketed a specific chromosomal segment approximately 37 cM in size, that improves both blood pressure and insulin resistance in the SHR. This segment also contains the Cd36 gene, which encodes a fatty acid transporter that was previously thought to be a candidate in the pathogenesis of insulin resistance and blood pressure. The PI proposes to use meiotic mapping in an interval specific segregating population to narrowly map the blood pressure locus on chromosome 4, derive a congenic subline that carries the relevant segment of chromosome 4 and test the potential role of Cd36 in blood pressure control and insulin resistance in transgenic SHR by overexpressing this gene.