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Biomedical subjects

A M Graham

Publications and source records attributed to A M Graham.

58 records · Page 4Linked to original sources
PubMedDate not supplied

Increased oxygen extraction as adaptation to acute renal ischemia.

Acute renal ischemia is an infrequently encountered clinical entity with occasionally devastating consequences. The renal compensation to acute ischemia is unknown and is the purpose of this report. Eight pigs were anesthetized and ventilated. Left atrial, aortic, CVP, left renal venous, and ureteral catheters were inserted. Renal blood flow (RBF) reduction was accomplished by the graded constriction of the left renal artery using a balloon occluder. Renal oxygen extraction ratio (RER, %), renal oxygen delivery (RO2D, cc/min per 100 gm), renal oxygen consumption (RVO2, cc/min/100 gm), creatinine clearance (CrCl, ml/min), and renal lactate production (delta [L], mg/min per hgm) were measured at baseline and following sequential 90-minute intervals of moderate and then severe left renal flow reduction. Significant increases in renal oxygen extraction were observed when RBF was severely limited (.30 +/- .05 vs .64 +/- .06, p < .01). CrCl decreased precipitously (16.5 +/- 4.6 vs 0.2 +/- 0.07, p < .05). Lactate production by the ischemic organs correlated with blood flow reduction (r = .546, p = .0034). In severe ischemia, healthy kidneys increase oxygen extraction to preserve oxygen consumption.

Acute Disease↗
PubMedDate not supplied

A persistent hindlimb ischemia model in the rabbit.

The study of new approaches for the treatment of limb-threatening ischemia has been hampered by the lack of a suitable animal model of persistent limb ischemia. We describe the development and evaluation of an animal model of persistent hindlimb ischemia, in which ischemia was induced in the left hindlimb of 28 rabbits by ligation of the distal external iliac artery and excision of the common and superficial femoral arteries. The severity of the ischemia and its relief in each animal were evaluated every 10 days postoperatively until day 40 (all animals) or day 90 (five animals). Nine animals developed superficial tissue necrosis in the foot, but no deaths were attributable to the ischemia-inducing procedure. Angiography demonstrated minimal collateralization and sluggish filling of distal vessels up to postoperative day 90. This was accompanied by a decrease at rest in the calf blood flow ratio (p < 0.005 vs day 0), an increase in lactic acid in the femoral venous blood (left vs right side, p < 0.002) up to postoperative day 40, and a decrease in the calf blood pressure ratio (p < 0.0001 vs day 0) up to day 90. Histologic study of the gastrocnemius muscle demonstrated evidence of atrophy and fibrosis in the left hindlimb. This model can be used to evaluate direct and indirect approaches to the treatment of chronic limb ischemia.

Animals↗