SUPERSENSITIVITY TO ISOPROTERENOL AND a NEW ADRENERGIC Β-Mimetic AGENT TRIMETHOQUINOL ON THE BLOOD PRESSURE OF THE RESERPINE TREATED RAT

Abstract

Supersensitivity to catecholamines in various organs after reserpine treatment has been reported by many investigators. Trendelenburg et al.(1) described that this action was associated with the impairment of uptake of catecholamines to adrenergic nerve terminals.On the other hand isoproterenol, one of the catecholamines, was not retained by the heart (2). Neither cocaine (3) nor denervation (4) could cause' supersensitivity to this amine.However, Fleming et al. (5) reported that after reserpine 'treatment the isolated ileum of rabbit became more sensitive to isoproterenol and recently Khan et al. (6) also showed that on the isolated rat fundus strip preparation reserpine and guanethidine increased the sensitivity to isoproterenol. But further evidences for these phenomena were not obtained.In a previous paper (7) authors reported briefly that on the blood pressure of the rat treated with reserpine the hypotensive action of isoproterenol was potentiated.In order to confirm our previous results, the effects of reserpine on the sensitivity to isoproterenol and a new adrenergic Q-stimulating agent trimethoquinol (8) were studied on the blood pressure of the rat. METHODS AND MATERIALSMale albino rats of Wistar strain were anesthetized with urethane 1.0-1.6 g/kg by subcutaneous injection.The blood pressure was recorded from the carotid artery with a mercury manometer or electrotransducer.Schedules of pretreatment with reserpine were as follows : The dose was 2 mg/kg/day on the first two days and 1 mg/kg/day on the next two days were given subcutaneously prior the experiments.Isoproterenol and trimethoquinol were given intravenously in doses ranging from 0.001 to 1,000 pg/kg.Injections were made into jugular vein via cannulated polyethylene tube.

Norepinephrine Directly Activates Adult Hippocampal Precursors via β3-Adrenergic Receptors

“…To study the influence of β adrenergic receptor stimulation on adult hippocampal progenitors, the β adrenergic receptor agonist, isoproterenol (2 mg/kg, Sigma) was used. The choice of drug dose was based on previous studies (Ozawa et al, 1969; Yuan et al, 2000), with 0.9% saline being used as the vehicle. Nestin-GFP mice received the drug via intraperitoneal injection, once daily for seven days.…”