Natriuretic peptide infusion reduces myocardial injury during acute ischemia/reperfusion

High doses of ANP and BNP exacerbate lipolysis in humans and the lipolytic effect of BNP is associated with cardiac triglyceride content in pigs

Drugs facilitating the cardioprotective effects of natriuretic peptides are introduced in heart failure treatment. ANP and BNP also stimulate lipolysis and increase circulating concentrations of free fatty acids (FFAs); an aspect, however, thought to be confined to primates. We examined the lipolytic effect of natriuretic peptide infusion in healthy young men and evaluated the effect in a porcine model of myocardial ischemia and reperfusion. Six young healthy normotensive men underwent infusion with ANP, BNP, or CNP for 20 min. Blood samples were collected before, during, and after infusion for measurement of FFAs. In a porcine model of myocardial ischemia and reperfusion, animals were infused for 3 h with either BNP (n = 7) or saline (n = 5). Blood samples were collected throughout the infusion period, and cardiac tissue was obtained after infusion for lipid analysis. In humans, ANP infusion dose-dependently increased the FFA concentration in plasma 2.5-10-fold (baseline vs. 0.05 μg/kg/min P < 0.002) and with BNP 1.6-3.5-fold (P = 0.001, baseline vs. 0.02 μg/kg/min) 30 min after initiation of infusion. Infusion of CNP did not affect plasma FFA. In pigs, BNP infusion induced a 3.5-fold increase in plasma FFA (P < 0.0001), which remained elevated throughout the infusion period. Triglyceride content in porcine right cardiac ventricle tissue increased ∼5.5 fold in animals infused with BNP (P = 0.02). Natriuretic peptide infusion has similar lipolytic activity in human and pig. Our data suggest that short-term infusion increases the cardiac lipid content, and that the pig is a suitable model for studies of long-term effects mediated by natriuretic peptides.

Natriuretic peptides in cardiometabolic regulation and disease

In the 30 years since the identification of the natriuretic peptides, their involvement in regulating fluid and blood pressure has become firmly established. Data indicating a role for these hormones in lifestyle-related metabolic and cardiovascular disorders have also accumulated over the past decade. Dysregulation of the natriuretic peptide system has been associated with obesity, glucose intolerance, type 2 diabetes mellitus, and essential hypertension. Moreover, the natriuretic peptides have been implicated in the protection against atherosclerosis, thrombosis, and myocardial ischaemia. All these conditions can coexist and potentially lead to heart failure, a syndrome associated with a functional natriuretic peptide deficiency despite high circulating concentrations of immunoreactive peptides. Therefore, dysregulation of the natriuretic peptide system, a 'natriuretic handicap', might be an important factor in the initiation and progression of metabolic dysfunction and its accompanying cardiovascular complications. This Review provides a summary of the natriuretic peptide system and its involvement in these cardiometabolic conditions. We propose that these peptides might have an integrating role in lifestyle-related metabolic and cardiovascular disorders.

Increased N-terminal CgA in circulation associated with cardiac reperfusion in pigs

Aim: Acute myocardial infarction causes neurohumoral activation characterized by increased sympathetic activity. CgA is a protein released during sympathoadrenal stress from neuroendocrine tissue. Recently, increased CgA concentrations in circulation have been reported and suggested to be an independent predictor of mortality after acute myocardial infarction. Materials & methods: Eighteen pigs underwent 1 h of regional myocardial ischemia followed by 3 h of reperfusion. Blood samples were collected every hour and plasma CgA was measured with two radioimmunoassays. Results: We found a 30% increase in plasma N-terminal CgA 1 h after re-establishment of coronary blood supply. On the other hand, plasma pancreastatin did not change in response to ischemia or reperfusion but decreased during the entire experiment. Conclusion: Our results suggest a differentiated CgA response in myocardial reperfusion after local cardiac anoxia that may reflect tissue-specific post-translational processing and release.