The Journal of surgical research
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To characterize the mesenteric alpha1- and alpha2-adrenoceptor populations in newborn piglets, an extracorporeal circuit was established to control intestinal blood flow in 0- to 2-day old and 10- to 14-day old animals. In both groups, alpha-adrenoceptor activation was first documented by observing dose-dependent increases in mesenteric perfusion pressure after intramesenteric arterial injection of alpha-adrenoceptor agonists. ⋯ In addition, mesenteric vasoconstrictor responses to other known vasoconstrictor agents--angiotensin II, neuropeptide Y, and a thromboxane A2 mimic (U-46619)--were not effected in either age group by prazosin or yohimbine, implying these agents act independently of alpha-adrenoceptor mechanisms. These data suggest that (1) there exists functional mesenteric alpha1- and alpha2-adrenoceptor-like activity in 10- to 14-day old piglets that, in 0- to 2-day old animals, is not specifically expressed; and (2) mesenteric alpha-adrenoceptor function becomes more selective as newborn piglets mature.
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Brain dysfunction is observed clinically in patients suffering from prolonged endotoxic shock. However, the etiology of brain dysfunction during sepsis is not clear. Certain researchers have reported that the decrease in brain catecholamines concentration during septic shock might be etiologically important in brain dysfunction. ⋯ In the CLP group, the brain tissue NE concentration had decreased in the forebrain, cerebellum, and brain stem (P < 0.05), and the tissue E concentration had decreased in the forebrain and brain stem by 24 hr after treatment (P < 0.05). An alteration in beta-adrenergic receptor density in the forebrain was observed at 24 hr in the CLP group (control, 237.0 +/- 14.0 fmole/mg protein; LPS i.v., 233.2 +/- 3.0 fmole/mg protein; sham-operated, 236.0 +/- 3.0 fmole/mg protein; CLP, 177.0 +/- 4.2 fmole/mg protein). These alterations in transmitter concentrations and beta-adrenergic density in the forebrain may be an important factor in septic encephalopathy.