Abstract:

Objective     Effects of transfection of the endothelial nitric oxide synthase (eNOS) gene were studied in rabbits with pulmonary hypertension  induced by left to right shunt or pulmonary hypertension crisis  induced by hypoxia . Methods    Eighteen pulmonary hypertension rabbits were divided into the experimental group(n=9) and the control group(n=9).In the experimental group,an adenoviral vector encoding eNOS was intratracheally transfected .The same dosage of saline was intratracheally transfected in the control group. The leftright shunt was ligated 4 days after transfection, while 10% oxygen was inhaled through endotracheal intubation. Changes of pulmonary artery systolic pressure (SPAP),mean pulmonary artery pressure(MPAP) and mean arterial pressure(MAP) were detected. Concentration of NO and transgene expression mRNA were investigated.  Results     Compared with that before transfection, pulmonary artery pressure  significantly decreased(P<0.01) in the experimental group, while there was no change in the control group. There were significant differences between two groups after transfection. 60min after hypoxia, all rabbits presented pulmonary hypertension crisis in the control group, but only 4 rabbits in the experimental group developed a crisis. Decreased PaO2 and MAP, increased PaCO2, SPAP and MPAP occurred in these two groups after hypoxia. But after the oxygen supply was restored, the variables recovered to normal levels in the experimental group. The variables of SPAP and MPAP were higher than their baseline, and MAP was lower in the control group. Comparing the variables (after  vs before hypoxia) between the control group and the experimental group, the increasing extent of SPAP,MPAP and PaCO2 and decreasing extent of MAP, CO and PaO2 in the experimental group were lower than those in the control group . With immunohistochemical staining,  expression of  the eNOS gene in alveolar endothelial cells, smooth muscle cells and endothelial cells of small pulmonary vessels of the experimental group increased more than that of the control group. The concentration of NO in the experimental group was higher than that in the control group. Agarose gel electrophoresis showed an amplified 3.77kb specific band in the experimental group, but not in the  control group. Conclusions    Intratracheal adenoviral-mediated eNOS gene transfection can reduce rabbits′ pulmonary hypertension induced by left-to-right shunt and decrease occurrence rate of pulmonary hypertension crisis.

Key words: Nitric oxide synthase; Adenovirus vector; Pulmonary hypertension; Gene therapy; Rabbit