Effects of Second-Hand Smoke and Gender on Infarct Size of Young Rats Exposed In Utero and in the Neonatal to Adolescent Period

Objectives. We sought to assess the effects of second-hand smoke (SHS) and gender on infarct size in young rats exposed in utero or in the neonatal to adolescent period, or both. Background. We previously demonstrated that exposure to SHS increases infarct size in rat model of ischemi and reperfusion, with dose-response relation. These results are consistent with epidemiologic studies demonstrating that SHS increases risk of death from heart disease. Methods. Thirty-one pregnant female rats were randomly divided into two groups: those exposed to SHS and control group (non-SHS). After 3 weeks, each rat had given birth to 10 to 12 rats. One hundred one neonatal rats were divided into four groups according to exposure to SHS in utero (SHSu) and randomized to SHS exposure in the neonatal to adolescent period (SHSna). After 12 weeks, all rats were subjected to 17 min of left coronary artery occlusion and 2 h of reperfusion. Results. Birth mortality was higher in the SHSu group than in the non-SHSu group (11.9% vs. 2.8%, p < 0.001). Body weight of neonatal rats at 3 and 4 weeks in the two SHSu groups was lower than that of rats in the two non-SHSu groups (p < 0.001). Exposure to SHSn increased endothelin-1 levels in plasm (p = 0.001). In all 70 young rats who survived the neonatal period, infarct size (Infarct mass/Risk are × 100%) was greater in the SHSn groups than in the non-SHSn groups (p = 0.005) and in the male groups than in the female groups (p < 0.001). Conclusions. Exposure to SHS in the neonatal to adolescent period and male gender increased myocardial infarct size in young rat model of ischemi and reperfusion. These results are consistent with epidemiologic studies demonstrating that SHS increases the health risk to neonates and adolescents.