Hemodynamic and metabolic responses to repeated blood sampling in the rat

Abstract

Repeated blood sampling (0.2 ml) in the conscious rat during the course of 10 cardiac index measurements using the Fick procedure did not alter the cardiac index as measured initially (285 ml x min-1 x kg-1). However, oxygen consumption and hematocrit were reduced 7-19% and 4-14%, respectively. Replacement of blood removed during sampling with donor blood prevented these responses, but also led to reduced cardiac index and arterial oxygen content, 22-28% and 10-21%, respectively. In additional studies in anesthetized rats, hemorrhage (25 ml/kg) increased plasma K+ by 29% and reduced plasma Na+ by 3%, suggesting that compensatory fluid replacement originated in cells as well as interstitium. This fluid replacement after blood loss helps sustain normal systemic hemodynamics, but blood loss can produce metabolic alterations that should be taken into account in any biochemical study. Although metabolic alterations can be prevented by replacing lost blood with donor blood, cardiopulmonary function may be adversely affected.

Acid-base disturbance during hemorrhage in rats: significant role of strong inorganic ions

“…Moreover, the acid-base response found during hemorrhage in KA rats was intermediate between that found in C and UA rats. Indeed, the finding in hemorrhaged C rats of a normal blood pH differs from the low blood pH usually found in previous studies performed in anesthetized hemorrhaged animals (17,20,37) and from the low blood pH found in anesthetized hemorrhaged rats in the present study. Unlike C rats, KA rats showed a primary metabolic acidosis reflected by a decrease in SID.…”

“…This latter may increase the activity of the anaerobic energyproducing systems or decrease aerobic energy-producing systems during hemorrhagic shock, thus raising lactic acid concentration of extracellular fluid and reducing plasma HCO 3 Ϫ concentration ([HCO 3 Ϫ ]) (17). However, hemorrhage also results in changes in the main plasma inorganic ions and proteins (6,10,16,18,(37)(38)(39)41).…”

Blood sampled in rats from right ventricle may not always be truly representative of a mixed venous sample

“…As inert gases are cleared in the lungs according to their solubility in blood and they are only replaced through the lower systemic circulation, higher or lower concentrations found in RV samples than those expected suggests a preferential collection of blood from the lower or upper systemic circulation, respectively. Gleeson et al 1983, Hilty et al 19891/respiratory (Truog et al 1979, Cain & Bradley 1983, Pages et al 1993, Alfaro et al 1995 and metabolic data (Walsh et al 1980, Souba et al 1990, mainly on the basis of analysis of arterio-venous blood differencesCorrespondence to: Dr Vicente Alfaro, Departamento de Fisiologla, Facultad de Biologia, Avda. Diagonal 645, 08071 Barcelona, Spain, Fax: 34-3-4110358, Tel: 34-3-4021526 Accepted 27 November 1995 and application of the Fick principle to calculate metabolic rates or cardiac output (QTl.…”

“…Since techniques of permanent cannulation of aorta, vena cava and right ventricle IRV)in rats and other small mammals were published (Popovic & Popovic 1960/ Popovic et al 1963/ Popovic & Kent 1964)/ they have been widely used in different studies to measure and calculate haemodynamic (Popovic & Kent 1964, Walsh et al 1976, Cain & Bradley 1983, Gleeson et al 1983, Hilty et al 19891/respiratory (Truog et al 1979, Cain & Bradley 1983, Pages et al 1993, Alfaro et al 1995 and metabolic data (Walsh et al 1980, Souba et al 1990, mainly on the basis of analysis of arterio-venous blood differences…”

Dried blood spot assay for estimation of metronidazole concentrations in rats and its application in single animal drug pharmacokinetic study

“…However, traditional bioanalytical methods require large volumes of biomatrix to accurately estimate the drug/metabolite concentrations. Withdrawal of large volumes of blood at each time point leads to haemodynamic changes in animal physiology, thus limits the number of samples that can be taken from a single animal [1].…”