Adrenaline responsiveness in borderline hypertension.
The effects of circulating adrenaline on cardiovascular function were studied in 14 subjects with borderline hypertension (BHT) and in 14 matched normotensive controls. Adrenaline was infused in stepwise increasing doses (0.1, 0.2, 0.4, and 0.8 nM/kg/min, i.v.). Noninvasive measurements of cardiac function (M-mode echocardiography) and blood pressure and blood sampling for determinations of venous plasma noradrenaline, adrenaline, cyclic AMP, and potassium were performed. Systolic and diastolic blood pressure responses to adrenaline were similar in both groups. Cardiac output was increased in BHT at rest but the signs of an increased myocardial contractility disappeared during adrenaline infusion. The BHT group displayed elevated heart rates and systemic vascular resistances over the full range of adrenaline concentrations studied but the responsiveness was similar in both groups. The beta 2-adrenoceptor-mediated increases in plasma cyclic AMP and decreases in plasma potassium were similar in the BHT and control groups. The results suggest an increased arousal in BHT at rest. Furthermore, beta 2-adrenoceptor sensitivity appears to be unaltered in BHT.
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D000242:Cyclic AMP / Q000097:blood; D004562:Electrocardiography; D004837:Epinephrine; D005260:Female; D006321:Heart / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D011188:Potassium / Q000097:blood; D013318:Stroke Volume / Q000187:drug effects
D000242:Cyclic AMP; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine