Effects of phentolamine on response to supine leg exercise of peripheral venous pressure and plasma catecholamine concentration. A Study in Patients with Mild Congestive Heart Failure

The present study examined the effects of phentolamine (PH) on the increments in peripheral venous pressure (ΔVP), and of plasma noradrenaline (ΔNA) and adrenaline (ΔA) concentration, in response to supine leg exercise. Peripheral venous pressure and plasma catecholamine concentrations were measured at rest and during exercise, before and after intravenous injection of PH (0.1 mg/kg) in 10 healthy volunteers (Group C), and in 42 patients with primarily left-sided heart diseases but without apparent right-sided or left-sided heart failure (NYHA class I, II). These cardiac patients were divided into 2 groups on the basis of ΔVP. Those with ΔVP below 35 mmH₂O comprised the normal group (Group N), and those with ΔVP more than 35 mmH₂O the abnormally high group (Group H). 1) In Group C, ΔVP changed only slightly from 11.1±2.8 (mean ±SE) to 4.9±1.7 mmH₂O with an intravenous injection of PH. On the other hand, PH caused a significant decrease in ΔVP from 22.2±2.3 to 10.4±2.3 mmH₂O in Group N (p<0.001), and from 52.7±3.4 to 17.0±12.4 mmH₂O in Group H (p<0.001). It was suggested that PH blocked the α-receptors of the systemic capacitance vessels, thereby inhibiting the constriction of these vessels. 2) Both NA at rest and ΔNA before PH were significantly higher in Group H than those in Groups C or N. ΔNA increased significantly after the PH injection in all 3 groups, i.e., from 0.038±0.013 (mean ±SE) to 0.282±0.051 ng/ml in Group C, from 0.056±0.013 to 0.279±0.034 ng/ml in Group N and from 0.279±0.034 to 0.839±0.103 ng/ml in Group H. The increase in ΔNA after PH was especially marked in Group H. It was suggested that the “sympathetic nervous activity” was increased in the patients with an impaired left ventricular pumping function. 3) PH caused a slight increase in ΔA in all groups, but there was no significant difference in ΔA before and after PH in the 3 groups.