Topical Nitroglycerin Ointment (2%) Applied to Forearm Skin Increases Skin Blood Flow

It was hypothesized that topical nitroglycerin ointment 2 nitropaste applied to the forearm would increase firearm skin blood flow SkBF. If so, nitropaste might be used to increase sensible heat flux from the forearm when it is applied under a forearm microclimate cooling system. Four men participated in four experiments each. The initial dose of nitropaste NTG was 7.5 mg. In each subsequent experiment approx. one week from the previous, the dose was increased by an additional 7.5 mg until a final dose of 30 mg was achieved. In each experiment, the men were treated with nitropaste after sitting for a 15-min control period in slightly warm ambient conditions Ta30 deg C, Tdpl2 deg C. Prior to and after nitropaste was applied to the volar surface of the forearm approx. 36 cm2, SkBF and heat flow were measured at the site by laser-Doppler velocimetry LDV. Heart rate was measured by ECG every 2.5 min. and every minute following application. Laser-Doppler Imaging LDI was used to measure changes in skin blood flux after application of 22.5 mg nitropaste in a single subject and was used in another experiment to measure the difference in SkBF between placebo-treated application sites and nitropaste-treated application sites. There were no differences in cardiovascular responses among doses. The data reported are the mean of all four doses used during the dose response tests. The LDI Pilot Tests showed increased cutaneous vasodilation, but the LDV measurements taken in the dose response tests did not. This revealed the inability of LDV probes to provide consistent data as LDV measures a small area and LDI is capable of scanning the entire area. The area under the LDV would not receive NTG, but the adjacent area would. Topical nitroglycerin paste was shown to affect systemic vascular tone as seen by decreased diastolic blood pressure DBP and pulse pressure PP from baseline to treatment.