关键词：
renin
vasopressin
atrial natriuretic peptide
intrathoracic pressure
extracellular volume
摘要：
In 12 conscious dogs, we investigated whether the angiotensin II-receptor antagonist losartan increases renal sodium excretion and urine volume during controlled mechanical ventilation (CMV) with positive end-expiratory pressure. In four experimental protocols, the dogs were extracellular volume (ECV) expanded (electrolyte solution, 0.5 ml . g(-1) . min(-1) iv) or not and received losartan (100 mu g . kg(-1) . min(-1) iv) or not. They breathed spontaneously during the Ist and 4th hour and received CMV with positive end-expiratory pressure (mean airway pressure 20 cmH(2)O) during the 2nd and 3rd hours. In the expansion group, dogs with losartan excreted similar to 18% more sodium (69 +/- 7 vs. 38 +/- 5 mu mol . min(-1) kg(-1)) and 15% more urine during the 2 h of CMV because of a higher glomerular filtration rate (5.3 +/- 0.3 vs. 4.5 +/- 0.2 ml . min(-1) . kg(-1)) and the tubular effects of losartan. In the group without expansion, sodium excretion (2.0 +/- 0.6 vs. 2.6 +/- 1.0 mu mol min-l kg-l) and glomerular filtration rate (3.8 +/- 0.3 vs. 3.8 +/- 0.4 ml . min(-1) . kg(-1)) did not change, and urine volume decreased similarly in both groups during CMV. Plasma vasopressin and aldosterone increased in both groups, and plasma renin activity increased from 4.9 +/- 0.7 to 7.8 +/- 1.3 ng ANG I . ml(-1) . h(-1) during CMV in nonexpanded dogs without losartan. Mean arterial pressure decreased by 10 mmHg in nonexpanded dogs with losartan. In conclusion, losartan increases sodium excretion and urine volume during CMV if the ECV is expanded. If the ECV is not expanded, a decrease in mean arterial blood pressure and/or an increase in aldosterone and vasopressin during CMV attenuates the renal effects of losartan.
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中文科技期刊
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