Dv. Zaretsky et al., Endothelin antagonism does not affect adrenal catecholamine secretion and system haemodynamics during acute stress in Wistar rats, J CARDIO PH, 36, 2000, pp. S374-S376
Citations number
9
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
In the present work we evaluated the role of circulating endothelin-1 (ET-1
) in haemodynamics and the adrenal medulla responses to stress using PD-142
893, a mixed endothelin-A- and -B- (ETA/ETB) receptor antagonist. Male Wist
ar rats were chronically instrumented with arterial and venous catheters an
d a microdialysis probe placed into the adrenal medulla. Stress was induced
by a 1 h period of immobilization. PD-142893 was infused (20 mug/kg/min) f
or 90 min starting 30 min before stress onset. Concentrations of norepineph
rine and epinephrine in dialysate samples were measured by high-performance
liquid chromatography (HPLC). At rest animals displayed a stable level of
norepinephrine (85 +/- 34 pg/ml) and epinephrine (176 +/- 57 pg/ml) in adre
nal perfusate and constant haemodynamic parameters. Stress increased adrena
l secretion (norepinephrine 206 +/- 50%, epinephrine 202 +/- 45%) associate
d with hypertension (peak 141 +/- 3 mmHg) and tachycardia (peak 505 +/- 5 b
pm). No significant changes in haemodynamics or of plasma catecholamine lev
els were observed during infusion of PD-142893. The antagonist did not sign
ificantly change the stress-induced increase in catecholamine secretion, ta
chycardia or hypertension. Thus, in Wistar rats, circulating ET-1 seems not
to be essential for blood pressure control or adrenal catecholamine secret
ion during acute stress.