Effects of hyperoxia and dimethylthiourea on neonatal pulmonary hemodynamics in piglets.
Exposure of piglets to 68-72 h of hyperoxia has previously been shown to blunt hypoxic pulmonary vasoconstriction (HPV). We tested the hypothesis that the administration of a scavenger of toxic oxygen radicals during exposure to hyperoxia would preserve HPV in piglets. Newborn piglets were kept in FIO2 greater than 0.90 for 68-72 h and compared to control animals kept in room air. Randomly selected animals from both groups were given the O2 metabolite scavenger, dimethylthiourea (DMTU) (500 mg/kg followed by 250 mg/kg/d), resulting in plasma levels of 2-6 mM. Following the oxygen or room air (RA) exposure period, piglets had pulmonary vascular resistance (PVR) measured following a 20 min exposure to alveolar hypoxia (FIO2 = 0.12). Both groups of RA-exposed animals (DMTU and saline treatment) as well as the hyperoxia-exposed saline group had almost 2-fold increases in PVR during exposure to hypoxia (P less than 0.05). Contrary to expectations, the PVR in the hyperoxia-exposed DMTU group did not rise significantly during hypoxia and the use of DMTU did not restore HPV by increasing PVR to levels greater than the hyperoxia/saline group (P = 0.70). Therefore DMTU does not appear to prevent hyperoxia-induced blunting of HPV in piglets.
Hoffmeister
A C
AC
Department of Pediatrics, University of Washington School of Medicine, Seattle 98195.
Jackson
J C
JC
Davis
K A
KA
Truog
W E
WE
D000818:Animals; D000831:Animals, Newborn; D006439:Hemodynamics / Q000187:drug effects; D000860:Hypoxia / Q000503:physiopathology; D008168:Lung / Q000187:drug effects* / Q000502:physiology / Q000503:physiopathology; D010100:Oxygen / Q000494:pharmacology*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D012119:Respiration; D013552:Swine; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
C038983:1,3-dimethylthiourea; D013890:Thiourea; D010100:Oxygen