RESPONSE OF LARGE SUPERFICIAL DORSAL HAND VEINS TO LOCALLY INFUSED NITROGLYCERINE IN YOUNG, NORMAL SUBJECTS

Nitroglycerine relaxes vascular smooth muscle and is routinely use to treat angina and congestive heart failure. However, in preliminary obs ervations of severe heart failure patients, nitroglycerine did not dil ate superficial veins, although the observations were made at the top of the distention-pressure relationship for superficial veins. Hence, the purpose of this study was to examine whether the venodilating effe cts of nitroglycerine could be demonstrated at lower distending pressu res. Dorsal hand vein diameter was measured using a linear variable di fferential transformer in 14 normal, healthy subjects, 20-34 years old . The distention-pressure response was obtained by applying 10-mmHg (1 mmHg = 133.3 Pa) increments of distending pressure from 10 to 50 mmHg . Distention-pressure curves constructed during randomized, single bli nd local intravenous infusions (constant rate of 0.1 mL/min) of dextro se or nitroglycerine (100 ng/min). No significant differences were obs erved during the study in heart rate or arterial pressure between dext rose and nitroglycerine. No difference in superficial dorsal venous di stension at any of the five applied distending pressures was observed during infused dextrose compared with infused nitroglycerine (10 mmHg, 0.21 +/- 0.03 vs. 0.23 +/- 0.04 mm; 20 mmHg, 0.63 +/- 0.06 vs. 0.63 /- 0.05 mm; 30 mmHg, 0.82 +/- 0.08 vs. 0.82 +/- 0.08 mm; 40 mmHg, 0.93 +/- 0.09 +/- 0.94 +/- 0.09 mm; 50 mmHg, 0.98 +/- 0.10 vs. 0.98 +/- 0. 09 mm; p = ns). Thus, locally infused nitroglycerine, at very high loc al concentrations, was unable to significantly vasodilate large superf icial dorsal hand veins of normals even at low distending pressures. F urther investigation is required of the actions of nitroglycerine on d ifferent venous beds and the arterial circulation, in addition to poss ible differences in response of subject populations such as congestive heart failure in which there may be different basal levels of resting venomotor tone.