Neurocirculatory regulation in cortisol-induced hypertension.
Effects of chronic glucocorticoid treatment on arterial baroreflex function and on cardiac beta- and vascular alpha-adrenoceptor-mediated responses were assessed in conscious, unrestrained Wistar-Kyoto rats. Cortisol (25 mg/kg/day) was administered for seven days using a subcutaneous reservoir pump. Arterial baroreflex-cardiac sensitivity was assessed by examining the relationship of the cardiac interbeat interval to the mean arterial blood pressure during phenylephrine or nitroprusside challenge; baroreflex-sympathoneural sensitivity was assessed from the ratio of the increase in the arterial norepinephrine concentration to the decrease in mean arterial pressure at 15 min during intravenous infusion of nitroprusside; cardiac beta-adrenoceptor-mediated responsiveness was estimated from heart rate responses to bolus-injected isoproterenol; and vascular alpha-adrenoceptor-mediated responsiveness was estimated from peak mean arterial pressure responses to bolus-injected phenylephrine. Cortisol treatment increased mean arterial pressure, decreased heart rate, and increased heart rate responses to isoproterenol, whereas baroreflex-vagal sensitivity, baroreflex-sympathoneural sensitivity, and pressor responses to phenylephrine were unaffected. The results indicate that hypertension due to chronic cortisol administration is not associated with decreased sensitivity of the baroreceptor-cardiac reflex. Baroreflex-sympathoneural sensitivity and alpha 1-adrenoceptor responsiveness also remain normal, whereas beta-adrenoceptor responsiveness is increased. The findings suggest that the pattern of neurocirculatory adjustment in glucocorticoid hypertension differs from that seen in other forms of hypertension.
Szemeredi
K
K
Clinical Neurosciences Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892.
Bagdy
G
G
Kopin
I J
IJ
Goldstein
D S
DS
D000818:Animals; D001775:Blood Circulation / Q000502:physiology*; D001794:Blood Pressure; D002395:Catecholamines / Q000097:blood; D006339:Heart Rate; D006854:Hydrocortisone / Q000494:pharmacology*; D006973:Hypertension / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000097:blood; D009420:Nervous System / Q000503:physiopathology*; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D011943:Receptors, Adrenergic, beta / Q000502:physiology
D002395:Catecholamines; D011943:Receptors, Adrenergic, beta; D009599:Nitroprusside; D010656:Phenylephrine; D008734:Methoxyhydroxyphenylglycol; C010117:3,4-dihydroxyphenylglycol; D006854:Hydrocortisone