EXPRESSION OF ANGIOTENSIN-CONVERTING ENZYME AND CHYMASE IN HUMAN ATRIA

Background A cardiac angiotensin Ii-generating system has been suspect ed to be involved in various cardiac pathological conditions, Both ang iotensin converting enzyme and human chymase can convert angiotensin I to angiotensin II, Objective To clarify the relative contributions of these two enzymatic pathways to angiotensin II generation in vivo. Me thods We assessed the expression levels of messenger RNA (mRNA) for co llagen type I alpha, transforming growth factor-beta(1), brain natriur etic peptide, angiotensin converting enzyme and chymase in right atria l appendages by competitive polymerase chain reaction and Northern blo t analyses, Correlations among the concentrations of these mRNA were a nalysed to obtain insight that might be important in understanding the formation of angiotensin II in atrial tissue,Results The collagen typ e I alpha and brain natriuretic peptide mRNA concentrations were corre lated significantly to the mean pulmonary arterial pressure, Multivari ate regression analysis revealed that the collagen type I alpha. mRNA concentration could be explained in terms of the brain natriuretic pep tide (P = 0.0005) and angiotensin converting enzyme (P= 0.0084) mRNA c oncentrations (r = 0.598, P< 0.0001), The chymase mRNA concentration h ad no significant correlation to the collagen type I alpha. mRNA conce ntration. Moreover, multiple regression analysis revealed that the tra nsforming growth factor-beta(1) mRNA concentration could be explained in terms of the angiotensin converting enzyme mRNA concentration alone (r = 0.424, P = 0.014), Conclusions The present results suggest that the level of angiotensin converting enzyme affects the tissue angioten sin II level in human atria; however, we could obtain no evidence that chymase is important in determining the tissue angiotensin II level.