Hemodynamic effects of lipids in humans

Evidence suggests lipid abnormalities may contribute to elevated blood pres sure, increased vascular resistance, and reduced arterial compliance among insulin-resistant subjects. In a study of 11 normal volunteers undergoing 4 -h-long infusions of Intralipid and heparin to raise plasma nonesterified f atty acids (NEFAs), we observed increases of blood pressure. In contrast, b lood pressure did not change in these same volunteers during a 4-h infusion of saline and heparin. To better characterize the hemodynamic responses to Intralipid and heparin, another group of 21 individuals, including both le an and obese volunteers, was studied after 3 wk on a controlled diet with 1 80 mmol sodium/day. Two and four hours after starting the infusions, plasma NEFAs increased by 134 and 111% in those receiving Intralipid and heparin, P< 0.01, whereas plasma NEFAs did not change in the first group of normal volunteers who received saline and heparin. The hemodynamic changes in lean and obese subjects in the second study were similar, and the results were combined. The infusion of Intralipid and heparin induced a significant incr ease in systolic (13.5 +/- 2.1 mmHg) and diastolic (8.0 +/- 1.5 mmHg) blood pressure as well as heart rate (9.4 +/- 1.4 beats/min). Small and large ar tery compliance decreased, and systemic vascular resistance rose. These dat a raise the possibility that lipid abnormalities associated with insulin re sistance contribute to the elevated blood pressure and heart rate as well a s the reduced vascular compliance observed in subjects with the cardiovascu lar risk factor cluster.