Atrial Natriuretic Peptide mRNA Regulation by p38- MAPK in the Perfused Amphibian Heart

Atrial natriuretic peptide (ANP) is a cardiac hormone involved in the regulation of fluid balance and blood pressure homeostasis. Using conventional reverse transcription and polymerase chain reaction and amplification, preproANP transcript from Rana ridibunda heart ventricle was cloned and characterized. Sequence analysis of the complete cDNA revealed an open reading frame for a 146- residue peptide, carrying a 17-residue ring at the Cterminus, characteristic of the natriuretic peptide family. Perfusion of Rana ridibunda myocardium under diverse stimuli such as mechanical, hyperosmotic or oxidative stress induced a rapid increase in the transcripts, which is accompanied by a significant increase in phosphorylated p38-MAPK levels. Furthermore, 1 µM SB203580, the selective p38-MAPK inhibitor, was found to abolish this increase suggesting the involvement of the p38-MAPK signalling pathway in the regulation of ANP mRNA expression.