Abstract: The present study was conducted to examine the expression of protein kinase Cα (PKCα) in pulmonary arterioles in broilers with pulmonary hypertension induced by cold temperature exposure and the relationship between PKCα and pulmonary vascular remodeling. One hundred and sixty Avian-2000 broilers were divided equally into a normal temperature control group (NT) and a low temperature group (LT) at 14-day-old of age. The group LT was subjected to low temperatures by lowering 1-2°C per day from 28 °C (day 14) down to 14-12 °C (day 21), and remained constant until the end of the experiment, while the group NT was still reared at normal temperatures (house temperature was 20 °C from day 21 on). PHS incidence was recorded. Ratio of right/total ventricle (RV/TV), packed cell volume (PCV) and hemoglobin (Hb) were measured at 24, 32, 39 and 45-day-old of age, respectively. Vessel wall area to vessel total area (WA/TA), mean media thickness in pulmonary arterioles (mMTPA) were determined using computer-image analytic software, and expression of PKCα in the pulmonary arterioles labeled by immunohistochemistry and quantified by measuring optical density (OD) using computer-image analytic software. PHS incidence amounted to 3.75% and 12.5% in groups NT and LT, respectively (P < 0.05). PCV in the group LT was elevated after day 32 (P < 0.05), and RV/TV ratio increased on day 45 (P < 0.05). Both the WA/TA and mMTPA of broilers in the group LT were significantly elevated (P < 0.05). There were no differences in OD value between the two groups before day 32 (P > 0.05). However, one week later (at day 39 of age), the OD value of broilers in the group LT was significantly increased (P < 0.05). The increased OD values were positively correlated with mMTPA and WA/TA. These results demonstrated that PKCα expression was increased in broilers with pulmonary hypertension, and increased expression of PKCα might enhance pulmonary vascular remodeling.

Key words: Pulmonary hypertension, Protein kinase Cα, Pulmonary vascular remodeling, Broilers, Cold temperature exposure