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 (delta VP), and of plasma noradrenaline (delta NA) and adrenaline (delta A) 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 delta VP. Those with delta VP below 35 mmH2O comprised the normal group (Group N), and those with delta VP more than 35 mmH2O the abnormally high group (Group H). 1) In Group C, delta VP 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 delta VP from 22.2 +/- 2.3 to 10.4 +/- 2.3 mmH2O in Group N (p less than 0.001), and from 52.7 +/- 3.4 to 17.0 +/- 12.4 mmH2O in Group H (p less than 0.001). It was suggested that PH blocked the alpha-receptors of the systemic capacitance vessels, thereby inhibiting the constriction of these vessels. 2) Both NA at rest and delta NA before PH were significantly higher in Group H than those in Groups C or N. delta NA 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 delta NA 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 delta A in all groups, but there was no significant difference in delta A before and after PH in the 3 groups.