title: Effects of changes in pO2, pCO2 and pH on the total vascular resistance of perfused cat kidneys.
abstract: 1. The effects of change in arterial P(O2), P(CO2) and pH on the total vascular resistance (RVR) of the perfused cat kidney have been separately measured and expressed as +/- percentage deviations from control values.2. Control levels in arterial blood were pH 7.38, P(-) (O2) 160 mm Hg, in equilibrium with 5% CO(2).3. Increase in P(O2) alone, in excess of 220 mm Hg, raised RVR reversibly reading 108% control levels at a P(O2) 280 mm Hg (P = < 0.001).4. High levels of P(O2) favoured the onset of ;outflow block', which was characterized by irreversible increase in RVR accompanied by rise in plasma filtration fraction (F.F.) and in the extraction ratio for p-aminohippuric acid (PAH extraction).5. Reduction in P(O2) to 80 mm Hg decreased RVR by 4% (P = < 0.001).6. RVR was not significantly affected by pH changes within the range 7.25-7.45. Lowering arterial pH to 7.15 raised RVR by 4% (P = < 0.001) reversibly. Increase in arterial pH to 7.56 raised RVR by 6% (P = < 0.001) reversibly.7. Changes in arterial P(CO2) produced large inverse reversible changes in RVR. Halving P(CO2) raised RVR by 18%; doubling P(CO2) decreased RVR by 25%.8. Changes in RVR caused by alteration of arterial pH or P(CO2) were not accompanied by changes either in F.F. or in PAH extraction.
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood*; D002415:Cats; D005919:Glomerular Filtration Rate; D007465:Iodohippuric Acid; D007668:Kidney / Q000502:physiology*; D010100:Oxygen / Q000097:blood*; D010477:Perfusion; D014655:Vascular Resistance
chemical_list: D002245:Carbon Dioxide; D007465:Iodohippuric Acid; D010100:Oxygen