Effects of Lactose in Saline Infusion on Electrolyte Alterations in Trypanosoma vivax-Infected Cattle.

Abstract

Alteration of serum electrolytes (Na+, K+, Cl-, and HCO3-) was studied in Zebu cattle experimentally infected with 11.0×106 Trypanosoma vivax. Another group of similarly infected cattle was intravenously infused with lactose in normal saline, at a dose rate of 0.5g/kg body weight as a function of the animal blood volumes of about 6-7% their body weights. Serum Na+ and Cl- concentrations showed significant (p<0.05) increases following decreasing parasitemia on days 6, 7, and 8 post infection (p.i.), whereas the greatest drops, resulting in hyponatremia and hypochloremia, occurred at the period when parasites were very scant in the blood. The Na+ and Cl- returned to normalcy between days 10 and 13p.i., coinciding with the second parasitemic wave. K+ values showed a nonsignificant decline following the decline of parasitemia, and rose to normal values thereafter, around the second wave of parasitemia. The HCO3- values were lowest when the parasites became numerous in the blood on day 3p.i., with a significant (p<0.05) decrease at peak parasitemia on day 5p.i. Subsequently, HCO3- concentrations increased when parasites became low in number in the peripheral circulation; thereafter, interrupted but significant (p<0.05) increases in HCO3- values occurred as the disease progressed. With the i.v. infusion of lactose in normal saline when the disease had been established, evidenced by peak parasitemia and declining packed cell volume (PCV), serum Na+ and Cl- remained normal as observed in the first uninfected uninfused group. The variations of K+ and HCO3- showed a similar pattern during the infusion. The values of all four electrolytes were relatively reduced immediately after and during the course of the infusion. The anion gaps were 20-22mM/liter for the uninfected group; 22-25mM/liter on days 3-5p.i. and 16-19mM/liter on days 6-13p.i, for the infected, uninfused group. Whereas infusion into the infected group produced an anion gap of 15-25mM/liter. The choice of saline as a solvent for lactose and the total infusion volume had no detrimental effect on the host's electrolytes and acid-base status; rather, the infusion ameliorated the aberrations in electrolytes associated with T. vivax in cattle.