Proopiomelanocortin-Derived Peptides and mRNA Are Expressed in Rat Heart. (Reannouncement with New Availability Information).

摘要

Proopiomelanocortin (POMC) is post-translationally processed to alpha-MSH, beta-endorphin, and a variety of other peptides, not only in the pituitary and brain, but in peripheral tissues as well. Beta-Endorphin and its immediate precursor beta-lipotropin (beta-LPH) have recently been identified in cardiac tissue suggesting that the POMC gene is expressed in heart, although neither the cellular localization nor the post-translational processing of cardiac POMC peptides has been fully characterized. The localization of beta-endorphin, as well as other opioid peptides, in cardiac tissue is consistent with extensive evidence that opiates produce direct effects on cardiac function, reducing cardiac output, coronary pressure, and heart rate. ACTH, alpha-MSH, and related ACTH fragments also exhibit potent, albeit opposing, cardio-regulatory activities, increasing rate and contractility, although their biosynthesis in cardiac tissue has not, as yet, been demonstrated. In the present study, we further characterized POMC processing in rat heart and also showed, using in situ hybridization, that POMC mRNA is localized within cardiac ventricular muscle cells.