Effect of ethylene glycol dinitrate on metabolism of catecholamines and on blood pressure reaction to re-exposure.

Abstract

<b>Minami, M., Okada, A., Takizawa, A., and Kubota, J. (1972).</b><i>Brit. J. industr. Med.,</i><b>29,</b> 321-327. <b>Effect of ethylene glycol dinitrate on metabolism of catecholamines and on blood pressure reaction to re-exposure.</b> Male Donryu rats were divided into two groups. One group was given 65 mg/kg per day of ethylene glycol dinitrate (EGDN) subcutaneously for five days and the other group received the same for 10 days. On the first, second, third, fourth, and fifth days after the last injection of EGDN catecholamines were estimated in the heart, brain, and adrenals and plasma 11-hydroxycorticosteroids and haemoglobin were estimated in blood. Urine samples were collected for 24 hours every other day before, during, and after the period of EGDN injection. After five successive doses of EGDN the concentration of catecholamines in the organs increased and urinary catecholamine excretion was a little greater than from the controls. Reinjection of EGDN caused prolonged irreversible depression of the blood pressure. After 10 successive doses of EGDN the concentrations of catecholamines in the organs were normal, but noradrenaline excretion in the urine was increased for three days. Reinjection of EGDN on the first day caused prolonged depression of blood pressure, but by five days the response had returned to the more transient depression observed in the controls. The probability of coronary spasm is considered to be greater in the condition found after five than in that after 10 successive injections because more noradrenaline was available in the cardiac muscle as well as adrenaline in the adrenals. After 10 successive injections the increased noradrenaline concentration in the urine reflected the raised noradrenaline level in the blood which could alleviate the depressant action of EGDN reinjection. The clinical significance of these findings is discussed.