PMID: 8949370Aug 1, 1996Paper

Contribution of the renin-angiotensin system to the variability of blood pressure in hypertensive rat after blockade of nitric oxide synthesis

Archives des maladies du coeur et des vaisseaux
O GouédardJ L Elghozi

Abstract

The aim of this study was to investigate, using spectral analysis, 1) the blood pressure (BP) variability changes in the conscious rat during blockade of nitric oxide (NO) synthesis by the L-arginine analogue L-NAME; 2) the involvement of the renin-angiotensin system in these modifications, using the angiotensin II AT1-receptor antagonist losartan. The blockade of the NO synthesis was made by infusion for 1 hour of a low dose (10 micrograms/kg/min, i.v.; n = 10) and a high dose (100 micrograms/kg/min, i.v.; n = 10) of L-NAME. The same treatment was applied in two further groups (n = 2 x 10) after a bolus of losartan (10 mg/kg, i.v.). The low dose of L-NAME increased systolic BP (SBP) on and after thirty min of infusion (+10 +/- 3 mmHg; p < 0.01). BP reached a maximum value 5 min after stopping L-NAME administration (+20 +/- 4 mmHg; p < 0.001). With the high dose of L-NAME, SBP increased immediately (5 min: +8 +/- 2 mmHg; p < 0.05) and reached a maximum at 40 min (+53 +/- 4 mmHg; p < 0.001); a bradycardia was observed (60 min: -44 +/- 13 batt/min; p < 0.01). The low dose of L-NAME increased the low-frequency component (LF: 0.02-0.2 Hz) of SBP variability (50 min: 6.7 +/- 1.7 mmHg2 vs 3.4 +/- 0.5 mmHg2; p < 0.05). The high dose o...Continue Reading

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