Measurements of vascular wall O/sub 2/ consumption following increased potassium

Vascular wall tissue PO/sub 2/ was measured with recessed cathode microelectrodes (tip diameters <5 mu m) in either strips or perfused segments of rabbit abdominal aortas (n=10). When bathed by saline with low K/sup +/ (4 mEq/L) oxygenated at 20 kPa, the minimum wall PO/sub 2/ was 6.65+or-1.56 (S.E.) kPa for seven aortic strips and 10.38+or-0.54 kPa for 16 measurements in three perfused aortic segments. Biphasic PO/sub 2/ increased significantly above control by +0.91+or-0.21 kPa (p<0.05), decreasing below control within 1 min in most cases. After 3 min, PO/sub 2/ decreased significantly below control by -0.72+or-0.24 kPa (p<0.05). O/sub 2/ disappearance rates measured after stopping flow to perfused segments were significantly faster (p<0.001) after relatively small changes in K/sup +/ (4 to 7 mEq/L) with little further increase at higher K/sup +/ up to 30 mEq/L. The data are consistent with elevated O/sub 2/ consumption as K/sup +/ increases. Perfused aortic segments had much greater metabolic changes than aortic strips for similar K/sup +/ increases.<
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