Studies on Vascular Responses to Noradrenaline in Patients with Essential Hypertension

Many studies on effects of noradrenaline infused to patients with essential hypertension have been performed in order to clarify an etiology of essen-tial hypertension. In the present report, the author determined the vascular reactivity to noradrenaline infused to normotensives and hypertensive patients at various infusion rates. The hemodynamic effects of noradrenaline infused to both groups were compared statistically. Patients with essential hypertension diagnosed by "casual" blood pressure were classified into 3 groups according to the values of basal blood pressure. Clinical findings and vascular reactivity to the infused noradrenaline in each group were studied. The antihypertensive drugs were administered orally to the patients with essential hypertension, and the vascular responses to the infused noradrenaline before and after the administration were compared. The findings obtained would have im-portant clinical implications. Materials and Methods Ten normotensives and 27 patients with essential hypertension who were admitted to our Hospital in Iwate Medical University were the subjects in this research. Their age ranged 25 to 60 years in both the normotensives and the patients with essential hypertension (mean age; 38 years in the normotensives and 41 years in the hypertensives). The normotensive patients were free from any sign of cardiovascular disease. The diagnostic criteria of hypertension was referred to the report of WHO Expert Committee on arterial hypertension, using "casual" blood pressure recording: (1) below 140/90 mmHg-normal range; (2) 160/95, mmHg and above- hypertensive range. These hypertensive patients by such casual blood pressure were classified into 3 groups mentioned above as follows: Group I; Basal blood pressure was in a normal range . Group II; Basal blood pressure 140-159 mmHg in systolic and/or 90-95 mmHg in diastolic. Group III; Basal blood pressure was in a hypertensive range. Electrocardiography and ocular fundscopic examination were carried out in all cases of hypertension. The subjects, who shows depression of above 1mm in ST segments in left ventricular leads and/or grade I and above in Keith-Wagner classification was regarded to be positive. Heart rate and brachial blood pressure were measured as the hemodynamic examination. Digital blood pressure and digital blood flow were determined as the peripheral vascular hemodynamics and peripheral vascular resistance was calculated from these values according to the law of Poisuille. The technics of these measurements were employed by method of KIMURA and KATO.