Cerebral blood flow determinations by radioactive microspheres in the subhuman primate: influence of unilateral internal carotid ligation, hypercapnic acidosis, and hypocapnic alkalosis.

Cerebral blood flow (CBF) was measured by electromagnetic and radioactive microsphere (RMS) techniques in the anubis baboon. Regional cerebral blood flows were calculated by distribution of intracardiac injections of RMS, labeled with one of three radionuclides: 51Cr, 85Sr, or 141Ce. In Group I (six animals, normocapnia), CBF's as estimated by electromagnetic measurement of internal carotid blood flow, were 65 +/- 10 and 74 +/- 4 (S.E.M.) ml. per minute per 100 Gm. for the right (RH) and left (LH) cerebral hemispheres, respectively; whereas CBF's as estimated by the RMS technique were 65 +/- 5 and 70 +/- 4 ml. per minute per 100 Gm., respectively, and these values were not significantly (p greater than 0.05) different. CBF, as determined by RMS techniques in Group 1, was not altered by unilateral internal carotid arterial ligation. In Group 2 (seven animals), arterial PCO2 was varied randomly from a low range (18 +/- 2 mm. Hg, L), to a middle range (PCO2 36 +/- 2, M), and a high range (PCO2 64 +/- 2, H), and CBF was measured by the RMS technique. During L, M, and H, CBF's were 44 +/- 10, 75 +/- 15, and 159 +/- 27 ml. per minute per 100 Gm., respectively, for RH, whereas CBF's were 44 +/- 10, 75 +/- 15, and 160 +/- 26 ml. per minute per 100 Gm., respectively, for LH. During H, RH and LH were significantly (p less than 0.05) greater than during L and M. Changes in regional CBF were uniform throughout the brain. These data demonstrate the correlation between CBF, as estimated by electromagnetic and RMS techniques, as well as confirm the adequacy of collateral cerebral circulation during unilateral carotid arterial ligation in the baboon. The usefulness of the RMS technique for hemispheric and regional CBF measurements is prevented also.