Chronic type IV phosphodiesterase inhibition protects glomerular filtration rate and renal and mesenteric blood flow in a zymosan-induced model of multiple organ dysfunction syndrome treated with norepinephrine

To examine the effects of chronic type IV phosphodiesterase (PDE4) inhibiti on 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 inhib ition with Ro 20-1724 at doses of either 0.3 or 2.0 mg/kg/min. Simultaneous ly, MODS was induced by intraperitoneal injection of zymosan (0.25mg/g). Me an arterial blood pressure, heart rate, renal blood flow, and superior mese nteric blood flow (SMABF) were measured at 48 h. Renal vascular resistance (RVR), superior mesenteric artery vascular resistance (SMAVR), and glomerul ar filtration rate were calculated. A dose-response effect of norepinephrin e was also evaluated at 48 h. Chronic Ro 20-1724 treatment prevented norepi nephrine-induced vasoconstriction in control rats. Inhibition of PDE4 with Ro 20-1724 (2.0 mg/kg/min) increased urinary cAMP, and attenuated the incre ase 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. Chro nic PDE4 inhibition protects renal function and mesenteric perfusion during MODS by increasing cAMP in the presence and absence of catecholamines. Hig her doses of PDE4 inhibition result in clinically tolerated decreases in me an arterial blood pressure, with improved end-organ function. Chronic PDE4 inhibition is protective, likely through cAMP-mediated attenuation of vasoc onstriction.