Adrenomedullin in Hypertension and Obesity

Adrenomedullin (AM), a biologically active peptide first detected in human pheochromocytoma, has been shown to be present in various tissues or organs, such as blood vessels, cardiac muscle, kidneys, and adipose tissue. AM exerts a wide range of actions, including those lessening cardiovascular damage associated with hypertension or obesityrelated disorders. This bioactive peptide was found to circulate in the human blood, and its plasma levels in hypertensive or obese patients were increased when compared with control subjects. Experiments with animal models of hypertension revealed a possible protective role of AM acting against elevation of blood pressure or hypertensive end-organ damage. In normotensive subjects, a rise in the plasma AM level was associated with future elevation of blood pressure. According to our recent study examining local residents, significant correlations were noted between plasma AM levels and body mass index, serum triglycerides, insulin, or high density lipoprotein cholesterol levels. Expression of AM in adipose tissue of an animal model of obesity was found to be higher than that of the control, and AM was produced and secreted from cultured adipocytes, where the AM receptor components were expressed. Animal experiments showed improved insulin resistance following AM infusion. Collectively, these findings suggest protective roles of AM acting against the progression of hypertensive organ damage and obesity-related metabolic disorders.