Circulation and acid-base balance in exercising goats at different body temperatures

Abstract

Thirty experiments were performed in two goats at an air temperature of +35 degrees C and a relative humidity of 33%. By means of heat exchangers, body core temperature (Tpaor) was adjusted to 39, 40.5, or 42 degrees C and maintained at these levels for 120 min. During the last 60 min the animals worked at a rate of 1.2 W/kg (treadmill, 3 km/h, 15%). Blood gases (arteriovenous O2 difference, Po2, Pco2), hemoglobin (Hb), blood lactate (LA), cardiac output (CO), blood pressure (MAP), heart rate (HR), metabolic rate (M), and respiratory evaporative heat loss (REHL) were determined. M, CO, HR, and Hb increased with exercise and were independent of Tpaor. At rest and exercise, REHL increased and Pco2 decreased at higher levels of Tpaor resulting in a respiratory alkalosis. During exercise this was accompanied by an increase in LA. At all instants, the concentrations of LA were higher at higher Tpaor. It is concluded that in a virtually nonsweating species like the goat the overall stress on the circulatory system caused by hyperthermia during exercise is relatively small while the behavior of blood LA is indicative of a temperature-dependent accumulation of LA also in the exercising muscle.

Circulatory Changes Associated With Heat Stroke: Observations in an Experimental Animal Model

“…The apparent increase in BF in late compared with early exercise could be due to our early exercise measurements possibly being taken before responses to the work load were invoked fully. The increased leg muscle BF just before collapse could be a response to a limitation of metabolic substrate availability (see below) or to lactate production associated with the high exercise and/or body temperature levels (Feistkorn et al 1984). The precipitous fall in BF is undoubtedly due to cessation not only of exercise but also of work involved in maintenance of normal posture, as the animal is now lying.…”

Characterization of a pig-to-goat orthotopic lung xenotransplantation model to study beyond hyperacute rejection

“…6 Moreover, goats are far more sensitive to xenogeneic whole blood than other species 9 and represent a well-established large animal model in cardiothoracic surgery. [10][11][12][13] Therefore we first investigated the existence of natural non-αGal xenoantibodies in goats and pigs and, on the basis of these results, tested whether their depletion would prolong an orthotopic xenograft lung in a discordant model.…”