Physical performance during sustained converting enzyme inhibition with Hoe 498 in conscious dogs

The effect of sustained converting enzyme (CE) inhibition on modest levels of exercise performance was investigated using German Shepherds. The dogs were trained to run on an inclined treadmill and to tolerate repeated jugular venous puncture. The effects of exercise were assessed by monitoring heart rate and respiratory rate and plasma catecholamine- and serum electrolyte concentrations on each of two control runs. Plasma CE- and renin activity were also determined. Inhibition of CE-activity was established thereafter by high dose treatment with 10 mg/kg Hoe 498 p.o. once daily for one week and the run repeated. These large doses of Hoe 498 were well tolerated. Neither running performance nor cardiorespiratory responses were altered by CE-inhibition. Plasma K+ and catecholamines were taken as measures of peripheral sympathetic activity, and CE-inhibition did not alter the increase in either of these in response to exercise. It is concluded that converting enzyme inhibition with Hoe 498 does not impair exercise performance despite any direct effects the loss of angiotensin II may have on reflex sympathetic functions.