THE INFLUENCE OF RESTRAINT ON BLOOD-PRESSURE IN THE RAT

We examined the influence of procedures used in blood pressure measure ment on blood pressure and the effects of antihypertensive agents. Sub jects were spontaneously hypertensive rats (SHR) and their Wistar/Kyot o (WKY) controls. Blood pressure was recorded by telemetry. Twenty-fou r h baseline pressure were measured, and the effect of minor handling on blood pressure and heart rate was examined. The influence of restra int such as is used for tail-cuff blood pressures was examined. The ef fects of three different antihypertensive drugs was also examined in t he SHR. In the home-cage environment, the SHRs showed higher systolic blood pressures, but had similar hypertensive responses to minor handl ing as the WKYs. Both strains had elevated heart rate and blood pressu re when restrained in the manner used for tail-cuff readings. The anti hypertensive effects of captopril and losartan in the SHR were unchang ed when the animals were restrained but the hypotensive effect of hydr alazine was greater. These results confirm that significant changes in heart rate and blood pressure can occur as a result of the minor proc edures frequently used in blood pressure recording in both SHR and WKY rats. This suggests that telemetry may have significant advantages as a method for continuous blood pressure monitoring. The pharmacologica l profile of antihypertensive drugs may well be different in animals w here telemetry is employed and are not subject to the stresses involve d in previous methods of monitoring blood pressure. (C) 1998 Elsevier Science Inc.