Partial reversal of guanethidine-induced adrenergic neuron blockade by acetaldehyde

The effects of acetaldehyde and acrolein on blood pressure in guanethidine-pretreated hypertensive rats

These experiments were undertaken to study the effect of the interaction of the antihypertensive agent guanethidine and two aldehydes possessing sympathomimetic activity on the blood pressure of spontaneously hypertensive rats (SHR). Acetaldehyde, when administered iv to acutely guanethidine-pretreated (15 mg/kg) SHRs under urethane anesthesia, caused a potentiated pressor response in the dose range of 3 to 40 mg/kg. When administered iv to chronically guanethidine-pretreated SHRs, a pressor response was noted at low doses and a depressor response at high doses. Acrolein (0.05 to 0.5 mg/kg) produced a pressor response at low doses and a depressor response at high doses in both acutely and chronically guanethidine-pretreated SHRs. Pressor responses, particularly to acetaldehyde, may be due to an enlarged tyramine-releasable pool, hyperreactivity of alpha adrenergic receptors of SHRs, or guanethidine inhibition of norepinephrine reuptake. Depressor responses to high doses of aldehydes may be attributed to vagal stimulation or direct vasodilation. It is concluded that there is a significant interaction between the aldehydes and guanethidine which may have implications for someone undergoing treatment with guanethidine for hypertension while being exposed to acetaldehyde and related compounds from ethanol and tobacco smoke.