Expression of angiotensin AT(1) and AT(2) receptors in adult rat cardiomyocytes after myocardial infarction - A single-cell reverse transcriptase-polymerase chain reaction study

The effector hormone of the renin-angiotensin system, angiotensin II, plays a major role in cardiovascular regulation, In rats, both angiotensin recep tor subtypes, AT(1) and AT(2), are up-regulated after myocardial infarction hut previous studies failed to identify the cell types which express the A T(2) receptor in the heart. To address this question we established a singl e-cell reverse transcriptase-polymerase chain reaction for AT(1) and AT(2) receptors to determine whether these receptor subtypes are expressed in adu lt rat cardiomyocytes before and 1 day after myocardial infarction, By lase r-assisted cell picking, section profiles of single cells without genomic D NA contamination were isolated. After dividing samples into two identical a liquots, polymerase chain reaction amplification for AT(1) and AT(2) recept ors was carried out and polymerase chain. reaction products were subjected to gel electrophoresis, Compared to control (n = 4) and sham-operated anima ls (n = 4), the number of cardiomyocytes expressing the AT(1) receptor mRNA 1 day after myocardial infarction (n = 4) was not changed (42% and 33% ver sus 45%, respectively). On the other hand, AT(2) receptor mRNA was expresse d in 8% and 13%, respectively, of cardiomyocytes gained from control (n = 4 ) and sham-operated animals (n = 4) and in 14% isolated after myocardial in farction (n = 4), These results demonstrate for the first time that the AT( 2) receptor is expressed in adult cardiomyocytes in vivo. They further sugg est that the previously observed upregulation of cardiac AT(1) and AT(2) re ceptors after myocardial infarction involves cell types other than cardiomy ocytes.