Effects Of Histamine On Pulmonary Vascular Remodeling In Broiler Chickens Induced By Low Ambient Temperature

The experiment aimed to find out the effects of two histamine receptor antagonists, chlorphenamine maleate and cimetidine, on pulmonary vascular remodeling induced by low ambient temperature in broiler chickens, which indicated that the role of histamine on pulmonary vascular remodeling. One hundred and forty 17-day broiler chickens were randomly divided into four groups:( 1) normal temperature group(NT); (2) low ambient temperature group(LT); (3) chlorphenamine maleate group in low ambient temperature (CMLT); (4) cimetidine group in low ambient temperature(CLT). At 24, 31, 38, 45 days of age, 10 birds were randomly taken from each group except CLT. At 31, 38 days of age, 10 birds were randomly taken from CLT. The weight of each bird was measured. The following three parameters were measured: the pulmonary artery pressure (PAP) by right cardiac catheter, the ascites heart index(AHI) and the packed cell volume (PC V). The lung, heart and liver of each bird was collected and fixed in 10% formalin. Paraffin sections were made. The slices were observed with optical microscope after hematoxylin and eosin staining; besides, the slices of lungs tissue stained with Weigert+VG were measured with an automated computerized image analyzer. The results were as follows:1. (1) The pulmonary artery pressure of CMLT was significantly lower than that of LT at 24 days of age (p<0.05). The pulmonary artery pressure of CLT were significantly lower than that of LT at 38 days of age (p<0.01). (2) At 24 days of age, the PCV of CMLT was significantly lower than that of LT (p<0.05). At 31 days of age, the PCV of CMLT was significantly higher than that of LT (p<0.05). (3) The AHI of CMLT was significantly less than that of LT (p<0.05) at 45 days of age.2. (1) In the pulmonary artery whose external diameter was less than 50um, the ratio of the thickness of medial membrane of CLT was significantly lower than that of LT at 38 days of age (p<0.05). (2)The ratio of muscularized artery of CLT was significantly lower than that of LT at 38 days of age (p<0.05). The ratio of nonmuscularized artery of CLT was significantly higher than that of LT at 31,38 days of age (p<0.05 or p<0.01).Chlorphenamine maleate had no obvious effect on the pulmonary vascular remodeling induced by low ambient temperature, so PAP of CMLT was increased at the late stage of experiment; Cimetidine could inhibit the pulmonary vascular remodeling induced by low ambient temperature effectively, so PAP of CLT was decreased at the late stage of experiment. These results indicated that histamine promoted the development of the pulmonary vascular remodeling and pulmonary hypertension induced by low ambient temperature in broiler chickens.