Macro- and microcirculatory effects of IL-15.

The recently isolated and cloned cytokine interleukin (IL)-15 was studied to ascertain its systemic and local cardiovascular effects. IL-15 was studied in rats anesthetized with 50 mg/kg sodium pentobarbital. In Group I, 10-50 micrograms of IL-15 were administered intravenously. Heart rate and arterial pressure decreased significantly for the duration of the study. In Group II, IL-15 was administered topically to the exposed cremaster muscle in four doses of 10 ng each. Heart rate and arterial pressure decreased significantly for the duration of the study. A1 and A2 arteriolar diameters decreased, but A3 diameters remained unchanged as determined by videomicroscopy. Vasodilation induced by either topical acetylcholine or nitroprusside was abolished by IL-15. Reduced heart rate and arterial pressure suggest reduced cardiac output. Arteriolar constriction due to abolished smooth muscle dilation was caused by IL-15.