Abstract

To examine the effects of chronic type IV phosphodiesterase (PDE4) inhibition on renal function and renal and mesenteric vascular resistance and blood flow in a sublethal model of multiple organ dysfunction syndrome (MODS) we used a prospective, randomized, controlled laboratory animal study. Twenty-eight rats had mini-infusion pumps placed to deliver vehicle or PDE4 inhibition with Ro 20-1724 at doses of either 0.3 or 2.0 μg/kg/min. Simultaneously, MODS was induced by intraperitoneal injection of zymosan (0.25 mg/g). Mean arterial blood pressure, heart rate, renal blood flow, and superior mesenteric blood flow (SMABF) were measured at 48 h. Renal vascular resistance (RVR), superior mesenteric artery vascular resistance (SMAVR), and glomerular filtration rate were calculated. A dose-response effect of norepinephrine was also evaluated at 48 h. Chronic Ro 20-1724 treatment prevented norepinephrine-induced vasoconstriction in control rats. Inhibition of PDE4 with Ro 20-1724 (2.0 μg/kg/min) increased urinary cAMP, and attenuated the increase in RVR and SMAVR (p < 0.05) and the decrease in RBF and SMABF (p < 0.05) that occurred from zymosan and norepinephrine. Glomerular filtration rate was also preserved (p < 0.05), despite a reduction in blood pressure. Chronic PDE4 inhibition protects renal function and mesenteric perfusion during MODS by increasing cAMP in the presence and absence of catecholamines. Higher doses of PDE4 inhibition result in clinically tolerated decreases in mean arterial blood pressure, with improved end-organ function. Chronic PDE4 inhibition is protective, likely through cAMP-mediated attenuation of vasoconstriction.