The Effect of Continuous Infusion of Dobutamine on the Maximal Forearm Skin Blood Flow and Plasma Neuropeptide Y Level in Patients with Congestive Heart Failure

To investigate whether continuous infusion of therapeutic doses of dobu tamine will influence the plasma neuropeptide Y (NPY) and the vasodilator capacity of nonacral skin in congestive heart failure (CHF) patients, the authors measured plasma NPY, norepinephrine (NE), and epinephrine (Epi) in 21 CHF patients, New York Heart Association (NYHA) function class III-IV, before and after four consecutive days' treatment by continuous infusion of dobutamine. Nine of these patients underwent laser Doppler flowmetry with a modified heat ing probe to measure the forearm skin blood flow for seventy minutes. They were measured at rest from room temperature to locally heated temperature of 42°C, a maneuver known to selectively and maximally vasodilate skin. Another 9 age-matched CHF patients, NYHA function class II, not requiring dobu tamine treatment, were treated with placebo to follow the same protocol. Mean arterial blood pressure and heart rate did not change significantly before and during treatment in both groups. The maximal forearm skin blood flow changed significantly from the control after dobutamine treatment in all the following four days (12.3 ± 2.4 versus 21.8 ± 4.4, 21.2±2.9, 22.3 ± 4.9, 23.0 ± 5.1 Volt, p < 0.05), but this was not observed in the placebo group (11. 8 ± 2. 9 versus 13.3 ± 2.4, 11.6 ± 1.8, 14.6 ± 2.5, 10. 0 ± 1.5, p = NS). The NPY, NE, and Epi did not show any alteration before and during four days' treat ments with dobutamine in 9 patients. Plasma NPY, NE, and Epi of 21 patients before dobutamine treatment were all elevated when compared with 115 age- matched control subjects (40 ± 3.0 versus 23.2 ± 0.9 pmole/L, p < 0.0005 for NPY; 3.7 ± 0.1 versus 2.4 ± 0.1 pmole/mL, p < 0.0005 for NE: and 1.9 ± 0.1 ver sus 1.6 ± 0.1 pmole/mL, p < 0.03 for Epi). Plasma NPY correlated better with NE than with Epi after dobutamine treatment. Hence the authors conclude: (1) the increment of skin blood flow by dobu tamine may be due to increased cardiac output or direct vasodilator effect. (2) NPY, NE, and Epi elevated in CHF, but they were not affected by acute stimula tion of sympathetic activity by dobutamine treatment. (3) The better correlation between NPY and NE indicates its origin from sympathetic nerve terminals, and NPY may play a role in the pathophysiology of CHF.