Dimethylthiourea Reverses Sepsis-Induced Pulmonary Hypertension in Piglets

Dimethylthiourea (DMTU), a putative hydroxyl radical scavenger, attenuates thromboxane generation and pulmonary hypertension in the piglet model of group B streptococcal (GBS) sepsis. This study tested the hypothesis that DMTU reverses ongoing GBS-induced pulmonary hypertension coincident with decreased thromboxane production. Piglets (n = 15) received a 60 min infusion of GBS (108efu/kg/min). Mean pulmonary artery pressure (P-pa), arterial blood gases (ABGs), and thromboxane B2 (TXB) levels were measured at 10 min intervals throughout the study. GBS infusion resulted in a marked increase in pulmonary artery pressure (mean ∆P-pa = 31 mm Hg) and a significant decline in PaO2 (mean = −80 torr) within 10 min of beginning the infusion. pH decreased from a mean of 7.47 to 7.37. DMTU, 750 mg/kg, or normal saline vehicle was infused over 10–15 min beginning 10 min after initiating GBS. P-pa decreased significantly within 10 min of DMTU infusion. Piglets receiving vehicle had a slow decline in P-pa. Piglets receiving DMTU also had an improvement in Pao2 and showed no further drop in pH. Piglets receiving vehicle had no improvement in Pao2 and demonstrated a continued decline in pH. TXB levels did not differ between the groups at any time interval. We conclude that DMTU can partially reverse GBS-induced pulmonary hypertension, but may function through mechanisms independent of thromboxane generation.