title: The exchange of calcium in larvae of the mosquito Aedes aegypti.
abstract: The exchange of labelled calcium between the external medium and the whole body was investigated in the larva of Aedes aegypti (L.) using a closed, two-compartmental model. The transport system for the uptake of Ca2+ was found to be saturable and obeyed Michaelis-Menten kinetics. The efficiency of the inward transport of calcium from dilute solutions was markedly reduced by starvation or by ruthenium-red, a selective inhibitor of Ca2+ activated ATPase, indicating that this transport system is energy dependent. Unlike transport systems for the major monovalent ions, the Ca2+ transport system is not located in the anal papillae, since removal of these organs resulted in enhanced Ca2+ fluxes. While over 95% of the calcium in the larva appeared to be distributed in the extracellular haemolymph, only 16% of the total calcium was readily exchangeable with the external medium; thus the majority of the calcium is apparently bound to haemolymph constituents. The results suggest that calcium pumps consisting of Ca2+ activated ATPases play an important role in the absorption of Ca2+ from dilute solutions in the gut and its reabsorption from the urine in the rectum.
mesh_terms: D000330:Aedes / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D007700:Kinetics; D007814:Larva / Q000378:metabolism; D012430:Ruthenium Red / Q000494:pharmacology
chemical_list: D012430:Ruthenium Red; D000252:Calcium-Transporting ATPases; D002118:Calcium