ACTIVE HCOg- SECRETION IN THE RECTAL SALT GLAND OF A MOSQUITO LARVA INHABITING NaHCO3-CO3 LAKES
نویسندگان
چکیده
1. Aedes dorsalis larvae are one of the few organisms capable of inhabiting hypersaline NaHCO3-CO3 lakes. Under laboratory conditions larvae can survive and develop normally in saline media with pH values of 10-5, HCO3~ concentrations of 250 mM, or CO3 ~ concentrations of 100 mM. 2. Despite ingestion of alkaline media at a rate equal to 130% of larval body wt/day, these insects regulated haemolymph pH (7"55-77o) and HCO3~ concentration (8-o-i8-5 mM) within narrow limits. 3. Analysis of fluid obtained by micropuncrure or microcannulation indicated that rectal secretion is an important mechanism of pH and HCO3~ regulation. 4. The lumen-to-haemocoel HCO3~ and CO3 ~ gradients generated by isolated, microcannulated recta were 21 :1 and 241 :1 , respectively. 5. Transepithelial potential in cannulated recta was — 14-2 to —25-3 mV (lumen negative), demonstrating that net HCO3~ secretion occurs against a large electrochemical gradient.
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