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Abstract

The femoral arterial blood flow in sheep was determined by implanting Doppler cuffs around the vessel which facilitated measurements over a prolonged period of time. Standardization of the cuffs was accomplished with an electronic integrator-digital time counter which converted Doppler frequency shifts to counts per mV/hr from which blood flow was estimated. Metabolic changes occurring in the hind limb of sheep following starvation were studied using femoral arterio-venous concentration differences of metabolites coupled with blood flow. Indwelling catheters were introduced into the femoral artery and vein to enable blood sampling. Two series of experiments were carried out in this study. Experiment I involved a four day starvation of two ewes. There was no statistical difference in the femoral arterial blood flow between fed and starved animals. In Experiment II another animal was utilized for four trials with the duration of starvation increased from four to six days. The adjusted mean fed blood flow of 78 + 2 ml/min decreased to a minimum of 45 + 3 ml/min on the sixth day of starvation. The average blood flow during the six days of starvation was 23.5 per cent lower than the pre-starvation level (P 0.05). The Doppler Flowmeter offers definite advantages over other methods of blood flow determinations by facilitating the measurement over prolonged periods without causing excitement of the animals. In this study the use of the Doppler Flowmeter and the continuous monitoring of blood flow through a period of 11 days has demonstrated that hind limb blood flow is reduced during starvation. The utilization of glucose and lactate was reduced during starvation by 62 and 39% respectively. There was a net production of 25 ± 1.5 and 20 ± 1 pg/min of alanine on the fifth and sixth days of starvation versus a net utilization of 23 ± 2 pig/min prior to starvation. The net alanine production during starvation provides a precursor for gluconeogenesis.