Effect of hypoventilation on blood ions and gases on experimental rat model

Abstract

Abstract : Hypoventilation is the inadequate breathing that is inadequate to meet the needs of the body or reduced lung function. The objective of this study was to investigate the effect of hypoventilation on blood ions and gases in the rat specially focusing on pH and blood magnesium (Mg2+); ionized and total, in the subject under experimental hypoventilation. Male Sprague-Dawley rats (250-300g) was selected and mechanical hypoventilation was applied by decreasing the rate of ventilation to as low as 40 cycles/min and the stroke volume was decreased down to 1.2 ml and the condition was continued during 20 minutes. The blood ions and gas was measured in the same experimental subject before and after hypoventilation. NOVA analyzer using an ion selective sensor for measuring ionized Mg2+ (iMg2+), calcium (Ca2+), potassium (K+), chlorine (C1‘), pH, Hematocrit (Hct) and blood gases. Total Mg2+ (tMg2+) in blood, plasma and RBC was measured by atomic absorption spectrophotometer. By direct comparison of initial values and experimental data in whole blood and red cells, the model has been shown to give realistic estimations of iMg2+ and tMg2+ in response to changes in each of these parameters. The blood pH significantly (p<0.001) decreased in the hypoventilated group and pC02 significantly increased (p<0.001) compared to the normal. In RBC, iMg2+ varies with the tMg2+, the concentration and availability of metabolites that bind Mg2+, the pH and the state of oxygenation. Only the significance difference was noticed in case of K* (p<0.05), iCa2+ (p<0.05) and iMg2+ (p<0.001) concentration. Hypoventilation is major cause of respiratory acidosis which disrupts the ionic and gaseous homeostasis. The model will be a useful tool for further investigation of hypoventilation and may reveals scopes for treatment and management strategy to recover the clinical condition.