Plasma catecholamines and adrenoceptors after chronic sinoaortic denervation in dogs.
Chronic sinoaortic denervation (SAD) performed by section of both carotid and aortic nerves induced a significant and sustained increase in blood pressure and heart rate in conscious dogs; under our experimental conditions, the values of systolic blood pressure and heart rate were never lower than 190 mmHg and 120 beats/min, respectively. The present long-term study (8 mo) investigated the time-course of plasma catecholamine levels and circulating blood cell adrenoceptor (leukocyte beta 2 and platelet alpha 2) number. Catecholamine plasma levels were highly correlated with the variations of leukocyte beta adrenoceptors (measured by [125I]cyanopindolol binding and characterized as a beta 2 receptor in dogs). These two parameters followed a biphasic pattern after SAD: during the first 2 mo, significant increases in noradrenaline and adrenaline levels were associated with a decrease in leukocyte beta 2 adrenoceptor number; from the 4th month, they slowly returned to normal values, although blood pressure remained elevated. By contrast, platelet alpha 2 adrenoceptor number (measured by [3H]yohimbine binding) did not follow this pattern since it remained lower than before SAD during the whole experiment. Finally, the development (but not the maintenance) of SAD-induced hypertension is associated with an increase in sympathetic tone. Only leukocyte beta 2 (and not platelet alpha 2) adrenoceptors are directly regulated by the endogenous levels of catecholamines.
Laboratoire de Pharmacologie Médicale et Clinique, INSERM U 317, Faculté de Médecine, Toulouse, France.
P
P
Valet
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C
Damase-Michel
J L
JL
Montastruc
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P
Montastruc
D000818:Animals; D001792:Blood Platelets / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000097:blood*; D002462:Cell Membrane / Q000187:drug effects; D003714:Denervation; D004082:Dihydroalprenolol; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D020120:Iodocyanopindolol; D007962:Leukocytes / Q000187:drug effects; D008297:Male; D010869:Pindolol / Q000031:analogs & derivatives; D011941:Receptors, Adrenergic / Q000187:drug effects*; D012849:Sinoatrial Node / Q000187:drug effects*; D013997:Time Factors
D002395:Catecholamines; D011941:Receptors, Adrenergic; D004082:Dihydroalprenolol; D020120:Iodocyanopindolol; D010869:Pindolol