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Biomedical subjects

B Grubb

Publications and source records attributed to B Grubb.

21 records · Page 2Linked to original sources
PubMed1977

Effect of arterial carbon dioxide on cerebral blood flow in ducks.

The purpose of this study was to determine the effect of arterial PCO2 on blood flow to the avian brain. Cerebral blood flow was measured on curarized, artificially ventilated Pekin ducks by the rate at which intra-arterially injected xenon-133 was cleared from the duck's brain. A two-component clearance curve resulted: the blood flow calculated from the fast and slow components was similar to the blood flow to mammalian grey and white matter, respectively. Hypercapnia markedly increased the fast component of blood flow, whereas hypocapnia had no effect on this component. These effects were not due to changes in blood pressure, which was independent of arterial PCO2. Blood flow calculated from the slow component was independent of arterial PCO2. We conclude that the lack of response to hypocapnia may contribute to the exceptional tolerance of birds to high altitude by maintaining normal cerebral blood flow.

Animals↗
PubMed1976

De novo synthesis of alanine by the perfused rat hindlimb.

Due to the disproportionately large production of alanine by muscle, it has been suggested that part of the alanine released by muscle is synthesized de novo by the transamination of glucose-derived pyruvate. This glucose-alanine conversion was quantitated in the isolated rat hindlimb perfused with a solution of bicarbonate buffer containing 2% albumin, 2.4% dextran, 2.5-15.9 mM glucose, 32-34% dog erythrocytes, and 0.05 muCi/ml [14C]glucose. Measurement of labeled alanine production allowed quantitation of de novo alanine synthesis. De novo derived alanine accounted for an average of 33% of the total alanine released by the perfused tissue (perfusate glucose concentration 8.3 mM), concurrently 2.7% of the glucose taken up by the limb was converted to alanine. By increasing the glucose concentration perfusing the muscle, both the rate of glucose uptake and de novo alanine release were increased. Addition of insulin to the perfusate (700 muU/ml) resulted in a significant increase in the rate of glucose uptake and de novo alanine production, but the rate of total alanine release was significantly decreased by the hormone. It was concluded that de novo alanine production accounts for a sizeable portion of the total alanine released by muscle, nevertheless a comparatively small fraction of the glucose carbons are actually transformed to alanine.

Alanine↗