Studies on the glomerular filtration rate and extracellular fluid volume in rhesus monkeys infected with Plasmodium knowlesi.

The glomerular filtration rate (GFR) and the extracellular fluid volume (ECV) were determined in 5 rhesus monkeys infected with P. knowlesi in comparison with 6 control monkeys by using 51Cr-EDTA. As the disappearance curve of the radioactivity showed a close fit to a double exponential equation, the data was therefore analysed by an open 2-compartment system. Results in the present study showed that the GFR was significantly reduced in the infected group. Both V1 and V2 were also slightly but not significantly decreased which resulted in the lower ECV in monkeys infected with P. knowlesi. As the GFR was reduced much more than ECV, therefore the mean transit time of 51Cr-EDTA in the infected group was longer than that of the normal group. All other intercompartment clearance and fractional transfer rate constants were also found to be lower in the infected group. These findings indicated that there was a delay in the distribution of 51Cr-EDTA between these 2 compartments in monkeys infected with P. knowlesi malaria.

Evidence of trapped red cells in the brain of rhesus monkey infected with Plasmodium knowlesi.

59Fe-labelled normal red cells and 51Cr-labelled P. knowlesi infected red cells were used as tracers for a study on the trapped red cells in the brain of rhesus monkeys infected with P. knowlesi. After instantaneous injection into a common carotid artery, blood was sampled from both of the internal jugular veins at various intervals. Results in 6 experiments on 3 infected monkeys showed that about 17% of infected red cells given was trapped in the capillaries of the brain of the infected monkeys. The remainder of the infected red cells travelled on the same flow rate as the normal red cells. As the volume for the flow of the former was less than that of the latter, the mean transit time of the infected red cells (-ty) was therefore shorter than that of the normal red cells (-th). The mean difference in volume was estimated to be 3.4% in the present study. These findings indicated that some of the P. knowlesi infected red cells were trapped in capillaries of the brains of monkeys infected with P. knowlesi.