Effect of glucocorticoids on cardiovascular reactivity in rats subjected to haemorrhagic shock.
The effect of glucocorticoids on the cardiovascular responses evoked by catecholamines and angiotensin in haemorrhagic shock was investigated in rats. In the intact preparation, cardiovascular responses to adrenaline, noradrenaline and angiotensin immediately after induction of haemorrhage improved the pressor responses of all the three pressor agents but it was ineffective when given in late stages of shock. Prednisolone and betamethasone improved selectively more the adrenaline responses. Treatment with all the three glucocorticoids improved the pressor responses evoked by noradrenaline and isoprenaline in isolated perfused hind-quarters of the rat but the pressor response evoked by adrenaline was only potentiated by prednisolone and betamethasone treatment. Glucocorticoid treatment in early stages prevented only the impairment of inotropic responses but did not improve the chronotropic responses in the isolated perfused heart of rat. The present study confirms the clinical observation that glucocorticoids prove beneficial only if administered in early stages of shock, and that this may be due to (i) prevention of the peripheral vasoconstrictor action of vasoactive substances such as catecholamines and angiotensin (released in shock) and (ii) prevention of the release of toxic factors such as a myocardial depressant factor.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D004837:Epinephrine / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects*; D006614:Hindlimb / Q000098:blood supply; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D012039:Regional Blood Flow / Q000187:drug effects; D012771:Shock, Hemorrhagic / Q000503:physiopathology*
D005938:Glucocorticoids; D000804:Angiotensin II; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine