Adrenalectomy in rats depresses hypoxic pulmonary vasoconstriction in vitro but does not attenuate the pulmonary hypertension of chronic hypoxia (part 7)

16 Aug

It has repeatedly been shown that angiotensin II pretreatment enhances the subsequent hypoxic pressor responses in preparations perfused with artificial solutions containing no glucocorticoids . The effect is present even in the absence of significant change of baseline perfusion pressure. Therefore, pressor responses to hypoxic challenges were repeated after angiotensin II injections. Then the responses of adrenalectomized rats to challenges with severe hypoxia were considerably increased and the dose-response curve did not differ from that obtained in control (nonadrenalectomized) preparations before angiotensin.II was added (Figure 1). The above described gradual increase of the baseline perfusion pressure in control lungs by the first series of hypoxic challenges resulted in a parallel shift of the second hypoxic pressor-response curve. Therefore, the responses to hypoxia still differed significantly between the groups after angiotensin II injections.

Acute effects of hypoxia in vivo: Both adrenalectomized and sham-operated rats kept in room air (controls for the experiment with chronic hypoxia, 17th day after surgery) showed similar pressor responses during 20 minbreathing of 10% O2. The maximal increase in pulmonary artery mean blood pressure was 15.4±3.1 mmHg in adrenalectomized rats (n=5) and 15.5±3.5 mmHg (n=5) in sham-operated rats. Buy cheap drugs at best pharmacy that you can fully rely upon: buy levitra professional and get chance to finally enjoy safe and amazingly simple shopping that costs you less.