Clinical and experimental hypertension : CHE
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Clin. Exp. Hypertens. · Sep 1993
The central effects of a nitric oxide synthase inhibitor (N omega-nitro-L-arginine) on blood pressure and plasma renin.
An endothelium-derived relaxing factor has been identified as nitric oxide (NO). Peripheral and central administration of nitric oxide synthase inhibitors result in an increase in renal sympathetic nerve activity and an increase in blood pressure. The goal of our study was to determine if the increase in blood pressure following central NO synthase inhibition with N omega-nitro-L-arginine (L-NNA) is caused by the release of renin. ⋯ However, intravenous infusion of the same dose (15 micrograms/min.) of L-NNA does not change blood pressure. We conclude that L-NNA acts directly within the central nervous system to increase blood pressure by a renin-independent mechanism. These results imply that central nitric oxide plays an important role in the regulation of blood pressure.
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Clin. Exp. Hypertens. · Sep 1993
Comparative StudyComparison of repeated measurement of ambulatory and clinic blood pressure readings in isolated systolic hypertension.
Repeated clinic blood pressure measurement was compared with non-invasive ambulatory blood pressure monitoring in 10 elderly subjects with persistent isolated systolic hypertension and 11 normotensive controls. Mean clinic blood pressures +/- Standard Deviation (SD), at visit 1 were 165/81 +/- 12/7 mmHg and 136/87 +/- 14/10 mmHg respectively. Subjects were assessed on three subsequent occasions at weekly intervals. ⋯ Daytime ambulatory readings aggregated from all four visits were normally distributed for both blood pressure components in both clinical groups. In the isolated systolic hypertension group the clinic systolic and diastolic blood pressure measurements corresponded to the 93rd and 85th percentiles of the ambulatory pressures respectively whereas in the normotensives the equivalent percentiles were 69 and 78. These results suggest a pressor response may largely account for the elevated systolic blood pressure seen in elderly subjects with sustained isolated systolic hypertension based on clinic readings.