Although generally a vasodilator, adenosine vasoconstricts cortical vessels in the kidney, reduces glomerular filtration rate (GFR), and increases medullary blood flow, effects likely to improve the medullary O2 deficiency characteristic of mammalian kidneys. To evaluate a possible role of adenosine in medullary O2 balance, we investigated the effect of adenosine upon cortical and medullary tissue Po2. Adenosine was infused into renal interstitium through chronically implanted capsules. Cortical and medullary Po2 were measured using sensitive dark-type O2 microelectrodes inserted into kidneys of anesthetized rats at the respective depths of 1.8 and 3.7 mm. Infusion of adenosine (0.1-0.5 μmol/min) increased medullary Po2 from 17 ± 3 (SE) to 40 ± 5 mmHg (P < 0.001) and decreased cortical Po2 from 64 ± 4 to 47 ± 3 mmHg (P < 0.001). After the infusion was stopped, Po2 returned to baseline at both sites. Coadministration of adenosine receptor antagonist 8-phenyltheophylline (0.01 μmol/min) prevented both cortical and medullary effects of adenosine. We concluded that adenosine could play an important protective and regulatory role in renal medullary O2 balance.
|Journal||American Journal of Physiology - Renal Physiology|
|Issue number||5 30-5|
|State||Published - 1991|
- Cortical partial tension of oxygen
- Intrarenal capsules
- Medullary hypoxia
- Medullary partial tension of oxygen