Effects of lactose in saline infusion on electrolyte alterations in Trypanosoma vivax-infected cattle

Alteration of serum electrolytes (Na+, K+, Cl-, and HCQ(3)(-)) was studied in Zebu cattle experimentally infected with 11.0 x 10(6) Trypanosoma vivax. Another group of similarly infected cattle was intravenously infused with lactose in normal saline, at a dose rate of 0.5 g/kg body weight as a funct ion of the animal blood volumes of about 6-7% their body weights. Serum Na and Cl- concentrations showed significant (p<0.05) increases following dec reasing parasitemia on days 6, 7, and 8 post infection (p.i.), whereas the greatest drops, resulting in hyponatremia and hypochloremia, occurred at th e period when parasites were very scant in the blood. The Na+ and Cl- retur ned to normalcy between days 10 and 13 p.i., coinciding with the second par asitemic wave. K+ values showed a nonsignificant decline following the decl ine of parasitemia, and rose to normal values thereafter, around the second wave of parasitemia. The HCO3- values were lowest when the parasites becam e numerous in the blood on day 3 p.i., with a significant (p<0.05) decrease at peak parasitemia on day 5 p.i. Subsequently, HCO3- concentrations incre ased when parasites became low in number in the peripheral circulation; the reafter, interrupted but significant (p<0.05) increases in HCO3- values occ urred as the disease progressed. With the i.v. infusion of lactose in norma l saline when the disease had been established, evidenced by peak parasitem ia and declining packed cell volume (PCV), serum Na+ and Cl- remained norma l 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 20-22 mM/liter for the uninfect ed group; 22-25 mM/liter on days 3-5 p.i. and 16-19 mM/liter on days 6-13 p .i. for the infected, uninfused group. Whereas infusion into the infected g roup produced an anion gap of 18-25 mM/liter. The choice of saline as a sol vent for lactose and the total infusion volume had no detrimental effect on the host's electrolytes and acid-base status; rather, the infusion amelior ated the aberrations in electrolytes associated with T. vivax in cattle.