Nature and control of chloride transport in insect absorptive epithelia
✍ Scribed by Phillips, J.E.; Wiens, C.; Audsley, N.; Jeffs, L.; Bilgen, T.; Meredith, J.
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 863 KB
- Volume
- 275
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Insect epithelia most commonly absorb from KC1-rich, low Na' fluids. This is true of the locust hindgut, which is functionally analogous to vertebrate kidney tubules. Active absorption of C1-at the apical membrane is the predominant transport process giving rise to a large short-circuit current (Isc) after stimulation by neuropeptides (CTSH, ITP) via CAMP as second messenger. This C1-transport is not coupled to or driven secondarily by Na', K' , HCO;, Ca", or M 2 + movements. An apical V-type H' ATPase acidifies the hindgut lumen but at a rate that is 10-15% of C1-dependent Isc. The evidence to date as to whether the resulting large apical proton gradient is used to drive C1-transport secondarily by an apical H' /C1-symport is mixed. Thus a primary mechanism of Cl-absorption remains an alternative possibility. The complete primary structure of a large neuropeptide stimulant (ITP: 72 amino acids) of locust ileal CI-transport has recently been deduced from its cDNA. This is the first putative insect neuropeptide hormone shown to stimulate ion transport across absorptive epithelia for which the primary sequence has been deduced. O 1996 Wiley-Liss, Inc.