L. De Caprio

Studies on the Nature of the Vasodilator Fibers Running in the Lumbar Sympathetic Chain of the Dog

These experiments were performed to further elucidate the nature of the vasodilator fibers running in the sympathetic chain in the dog. The electrostimulation of the lumbar sympathetic trunk caused vasoconstriction in the perfused hind limb which inverted to vasodilatation after guanethidine was administered. This vasodilator response is mediated by cholinergic fibers since it was completely abolished by atropine. The observation, furthermore, that hexamethonium completely nullified both vasodilator and vasoconstrictor responses to the electrostimulation of the sympathetic chain indicates that both vasoconstrictor and vasodilator fibers, which are activated during the stimulation of the sympathetic chain, are preganglionic in nature.

Regression of left ventricular hypertrophy and improvement of renal hemodynamics in hypertensive patients treated with quinapril

SummaryOf 17 patients with mild to moderate essential hypertension, 8 showed echocardiographic evidence of left ventricular hypertrophy. Cardiac and renal function evaluated by glomerular filtration rate (GFR) were studied in all patients before and after 20 weeks of quinapril treatment. Systolic pressure decreased from 174.7±16.7 to 131.7±7.7 mmHg (p<.0001) and diastolic pressure decreased from 101.8±9.8 to 80±4.3 mmHg (p<.0001). Left ventricular mass index decreased in the eight patients with left ventricular hypertrophy (p<.01). Basal values of GFR were lower than normal in 41% of all patients; GFR increased significantly after 20 weeks of treatment (from 96.5±32.3 to 108.6±31.12 ml/min, p<.01); it decreased in only one patient. Patients reported few adverse effects to quinapril, and no important clinical laboratory abnormality was observed. Quinapril not only lowered arterial pressure, but it had a distinct effect on regression of left ventricular hypertrophy and favorable effects on renal function.

Studies on the Mechanism of Reflex Vasodilatation

This study was designed to investigate whether the cholinergic system is involved in the genesis of the reflex vasodilatation which follows the systemic hypertension induced by fast intravenous injection of norepinephrine in the dog. Accordingly, in 7 dogs the gracilis muscle was isolated and perfused and the reflex evoked. The analysis of the integrated areas of vasodilatation after atropine pretreatment showed a significant decrease of the reflex response in the perfused circulation. In fact, the mean value of the integrated areas of vasodilatation which was 66 ± 8 mm Hg/min in the control condition, was reduced to 45 ± 4 mm Hg/min after administration of atropine in the gracilis artery; meanwhile the integrated areas of systemic hypertension did not show any change. Phentolamine intra-arterial administration completely abolished the reflex. These results suggest the existence of a cholinergic component in the reflex vasodilatation induced by transitory baroreceptorial stimulation.