DETERMINATION OF AMINOPEPTIDASE-X ACTIVITY IN TISSUES OF NORMOTENSIVEAND HYPERTENSIVE RATS BY CAPILLARY ELECTROPHORESIS

Aminopeptidase X, an enzyme that degrades angiotensin I to des-asp-ang iotensin I, was determined in the lung, liver, kidney, plasma, endothe lium and aortic smooth muscle of the spontaneously hypertensive rat (S HR) and its normotensive control, the Wistar Kyoto rat (WKY). The enzy me activity in the lung, kidney, plasma and endothelium of the SHR was elevated and this supports an earlier suggestion that in certain crit ical tissues of the SHR, the degradation of angiotensin I is shunted i n favour of the des-asp-angiotensin I pathway. In these tissues, the f ormation of presser angiotensin II would be curtailed and that of des- asp-angiotensin I enhanced. As des-asp-angiotensin I lacks direct vaso pressor action, its preferential formation over that of angiotensin II could be a physiological response to the prevailing hypertension in t he SHR. (C) 1997 Elsevier Science B.V.