The effects of serum estrogen levels on hypoxemia and blood nitric oxide levels in experimental hepatopulmonary syndrome.
BACKGROUND
: Hepatopulmonary syndrome (HPS) is a well-defined cause of hypoxemia in patients who have liver disease due to abnormal intrapulmonary vascular dilatation. The pulmonary symptoms of HPS are the result of oxygenation defects that occur as a result of acquired dilatations of the pulmonary blood vessels. In this study, we investigated the effects of estrogen and nitric oxide (NO) in experimental HPS, especially in intrapulmonary vascular dilatation.


METHODS
: Fifty female Sprague-Dawley rats were used in this study. The animals were divided into five groups of 10. Group l (the control group): the common bile duct (CBD) was dissected but not ligated. Group 2 (the cirrhosis group): the CBD was ligated. Group 3 (the cirrhosis+oophorectomized group): the CBD was ligated and a bilateral oophorectomy performed. Group 4 (the cirrhosis+estrogen group): the CBD was ligated and exogenous estrogen (5000U/kg) given. Group 5 (the control+estrogen group): the CBD was dissected, but not ligated and exogenous estrogen (5000U/kg) given. A 5-week waiting period was observed for the development of cirrhosis and the rats' lungs and liver were taken for histopathological examination. Pulmonary vessel diameters were measured. The total bilirubin, direct bilirubin, alkaline phosphatase (ALP), estrogen and serum nitric oxide (NO) levels were measured.


RESULTS
: The mean perialveolar vessel diameters were significantly higher in the cirrhotic rats (Groups 2, 3, and 4) than the control and control+estrogen administered groups. Again, when we compared the cirrhosis+oophorectomized group and the cirrhosis+estrogen group, the mean perialveolar vessel diameter was significantly lower in the cirrhosis+oophorectomized group than the cirrhosis+estrogen administered group (p=0.001). The mean perialveolar vessel diameter in the cirrhosis+oophorectomized group was significantly lower than the cirrhosis group (p=0.01). When we compared the cirrhotic rats (Groups 2, 3, and 4) and the control group, the plasma NO levels were significantly higher in the cirrhotic rats than the control group (p<0.001). Among the cirrhotic rats, the plasma NO levels were 47.2+/-0.7 and 70.9+/-1.5mumol/l in the cirrhosis+oophorectomized group and the cirrhosis+estrogen administered group, respectively (p=0.004).


CONCLUSIONS
: We consider that raised levels of estrogen have a potential role in intrapulmonary vascular dilatation and hypoxemia in HPS. Also, we consider that this effect of estrogen is due to increased levels of NO. Antiestrogenic surgical therapy may decrease the serum estrogen and NO levels, and may decrease the diameter of perialveolar vessels in order to relieve hypoxia in cirrhotic cases.
Yol
Serdar
S
Department of General Surgery, Selcuk University, Meram Medical Faculty, Turkey.
Erikoglu
Mehmet
M
Toprak
Sükrü Salih
SS
Tavlı
Sakir
S
Tavlı
Lema
L