Differential gene expression of adrenomedullin receptors in pressure- and volume-overloaded heart--role of angiotensin II

Left ventricular (LV) adrenomedullin (AM) gene expression differs between pressure overload (POL) and volume overload (VOL) and angiotensin II could be a critical stimulator of AM gene expression in POL and VOL models. Calcitonin receptor-like receptor (CRLR) co-expressed with receptor activity modifying protein 2 (RAMP2) or RAMP3 functions as an AM receptor. Levels of CRLR, RAMP2 and RAMP3 mRNA that were significantly increased within 24 h returned to the basal level at 5 days after the imposition of POL in the present study. In contrast, mRNA levels of CRLR and RAMP2 gradually increased over 6 weeks after the imposition of VOL. Continuous infusion of angiotensin II stimulated LV AM gene and AM receptor gene expression independently of LV peak-systolic and LV end-diastolic pressure. The gene expression of LV AM receptors increased in different types of cardiac overload. The present study revealed an intimate association between the AM signaling system and angiotensin II.