Insulin and hypertension: a causal relationship?

Although considerable evidence lends credence to the association between insulin and hypertension, the precise nature of this link remains elusive. Recent observations indicating that insulin may modulate vascular smooth muscle contractility has given yet another interesting twist to this intriguing association. The finding that insulin can directly alter smooth muscle calcium transients as well as attenuate the effect of other vasoconstrictor amines suggests that this metabolic hormone may also play an important hemodynamic role under pathophysiologic conditions. However, the independent contribution of insulin resistance toward an increase in BP is probably smaller and more complex than is often emphasized and to assume that insulin is directly linked to a rise in BP in hypertensive subjects is perhaps oversimplistic and incorrect. Future research efforts should be targeted at examining the effects of insulin on vascular smooth muscle contractility in hypertensive subjects and the interaction of insulin with other vasoactive peptides.