Effect of 5 alpha-pregnan-3 alpha-ol-20-one on nitric oxide biosynthesis and plasma volume in rats.
Plasma 5 alpha-pregnan-3 alpha-ol-20-one (pregnan) levels and nitric oxide (NO) biosynthesis increase during pregnancy. These factors have independently been implicated in the control of blood pressure and volume. We wished to determine whether pregnan might be responsible both for the increase in NO biosynthesis and for the increase in plasma volume observed during pregnancy. Virgin female Long-Evans rats were implanted with indwelling cannulas and maintained on a low nitrate/nitrite diet. After the rats recovered from surgery, 500 microg of pregnan or vehicle were given daily for 2 days. NO biosynthesis and plasma volume were measured in conscious animals before and after treatment. Pregnan caused a significant increase in NO biosynthesis (1.9 +/- 0.8 micromol/24 h, n = 10) compared with the vehicle-treated control group (0.3 +/- 0.4 micromol/24 h, n = 10, P < 0.05). Similarly, there was a significant increase in plasma volume in the pregnan-treated group (0.7 +/- 0.2 ml/100 g, n = 11) compared with the vehicle-treated control group (0.2 +/- 0.1 ml/100 g, n = 11, P < 0.05). These results confirm that pregnan can mimic pregnancy by its ability to increase both NO biosynthesis and plasma volume.
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Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada. susan.Jacobs@ualberta.ca
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D000818:Animals; D001810:Blood Volume / Q000187:drug effects; D005260:Female; D009566:Nitrates / Q000652:urine; D009569:Nitric Oxide / Q000096:biosynthesis*; D009573:Nitrites / Q000652:urine; D010953:Plasma Volume / Q000187:drug effects*; D011280:Pregnanolone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; C053623:pregnane-20-one; D011280:Pregnanolone