Acute regulation of lymphocyte beta 2-adrenoceptors is altered in patients with essential hypertension.
The effects of acute stimulation of the sympathetic activity by dynamic exercise on lymphocyte beta 2-adrenoceptor density [assessed by (-)-125iodocyanopindolol (ICYP) binding] and responsiveness [10 mumol/l isoprenaline-induced cyclic adenosine monophosphate (cAMP) increases] were studied in 10 normotensive (Pdiast < 90 mmHg) volunteers and in 10 patients with established essential hypertension (Pdiast > 95 mmHg). In normotensives, dynamic exercise on a bicycle (80% of maximum heart rate) for 15 min led to an increase in lymphocyte beta 2-adrenoceptor density from 1080 +/- 77 to 2033 +/- 152 ICYP binding sites/cell; concomitantly isoprenaline-induced increase in lymphocyte cAMP was enhanced. This effect appears to be mediated by beta 2-adrenoceptor stimulation, since the exercise-induced increase in beta 2-adrenoceptor density was markedly attenuated by pretreatment of the volunteers with propranolol (5 mg intravenously 45 min before exercise), but not by pretreatment with the beta 1-selective antagonist bisoprolol (2.5 mg intravenously 30 min before exercise). In patients with essential hypertension, lymphocyte beta 2-adrenoceptor density (1512 +/- 101 ICYP binding sites/cell) was significantly higher than in controls (P < 0.05); the same held true for isoprenaline-induced cAMP increases. In these patients, however, dynamic exercise caused only a slight increase in lymphocyte beta 2-adrenoceptor density (to 1859 +/- 154 ICYP binding sites/cell) and in isoprenaline-induced cAMP increases. From these results it is concluded that in essential hypertension acute regulation of the beta-adrenoceptor/adenylate cyclase system is impaired.
Brodde
O E
OE
Biochemical Research Laboratory, University of Essen, Federal Republic of Germany.
Daul
A E
AE
O'Hara
N
N
Wang
X L
XL
Bock
K D
KD
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010869:Pindolol / Q000031:analogs & derivatives; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*
D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D010869:Pindolol; D000242:Cyclic AMP; D007545:Isoproterenol