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Journal of Experimental Biology, Vol 177, Issue 1 273-285, Copyright © 1993 by Company of Biologists
JOURNAL ARTICLES |
SH Maddrell, MJ O'Donnell and R Caffrey
Department of Zoology, Cambridge, UK.
The blood-sucking insect Rhodnius prolixus rapidly eliminates a Na(+)-rich K(+)-poor urine after its large meals. K(+)-rich fluid is first secreted by the upper Malpighian tubules and passes to the lower tubules where most of the potassium is reabsorbed. During the initial stimulation of the tubules, the lower tubules must be activated first to avoid loss of potassium. The major element in this is that they respond more rapidly than do the upper tubules to particular hormonal concentrations rather than that they react to lower hormonal concentrations than do the upper tubules. During subsequent diuresis, regulation of the haemolymph potassium concentration depends on three cooperative homoeostatic mechanisms in the tubules. A fall in potassium concentration of the medium bathing the tubules causes (i) a decrease in the rate of fluid secretion by the upper tubules, (ii) a decrease in potassium concentration in the fluid secreted by the upper tubules and (iii) an increase in the rate of potassium absorption by the lower tubules. The tubules respond in the opposite direction to an increase in potassium concentration of the medium. As a result, the potassium concentration of the urine can be adjusted to match the potassium concentration of the fluids absorbed from the gut, so that the potassium concentration of the insect's haemolymph remains unaltered.
This article has been cited by other articles:
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  A. Donini, M. J. O'Donnell, and I. Orchard Differential actions of diuretic factors on the Malpighian tubules of Rhodnius prolixus J. Exp. Biol., January 1, 2008; 211(1): 42 - 48. [Abstract] [Full Text] [PDF]
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M. S. Santini and J. R. Ronderos Allatotropin-like peptide released by Malpighian tubules induces hindgut activity associated with diuresis in the Chagas disease vector Triatoma infestans (Klug) J. Exp. Biol., June 1, 2007; 210(11): 1986 - 1991. [Abstract] [Full Text] [PDF]
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J. P. Ianowski and M. J. O'Donnell Electrochemical gradients for Na+, K+, Cl- and H+ across the apical membrane in Malpighian (renal) tubule cells of Rhodnius prolixus J. Exp. Biol., May 15, 2006; 209(10): 1964 - 1975. [Abstract] [Full Text] [PDF]
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S. L. Litwiller, M. J. O'Donnell, and P. A. Wright Rapid increase in the partial pressure of NH3 on the cutaneous surface of air-exposed mangrove killifish, Rivulus marmoratus J. Exp. Biol., May 1, 2006; 209(9): 1737 - 1745. [Abstract] [Full Text] [PDF]
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J. P. Ianowski, R. J. Christensen, and M. J. O'Donnell Na+ competes with K+ in bumetanide-sensitive transport by Malpighian tubules of Rhodnius prolixus J. Exp. Biol., October 1, 2004; 207(21): 3707 - 3716. [Abstract] [Full Text] [PDF]
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J. P. Ianowski and M. J. O'Donnell Basolateral ion transport mechanisms during fluid secretion by Drosophila Malpighian tubules: Na+ recycling, Na+:K+:2Cl- cotransport and Cl- conductance J. Exp. Biol., July 1, 2004; 207(15): 2599 - 2609. [Abstract] [Full Text] [PDF]
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K. W. Beyenbach Transport mechanisms of diuresis in Malpighian tubules of insects J. Exp. Biol., November 1, 2003; 206(21): 3845 - 3856. [Abstract] [Full Text] [PDF]
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J. P. Ianowski, R. J. Christensen, and M. J. O'Donnell Intracellular ion activities in Malpighian tubule cells of Rhodnius prolixus: evaluation of Na+-K+-2Cl- cotransport across the basolateral membrane J. Exp. Biol., June 1, 2002; 205(11): 1645 - 1655. [Abstract] [Full Text] [PDF]
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S. Linton and M. O'Donnell Contributions of K+:Cl- cotransport and Na+/K+-ATPase to basolateral ion transport in malpighian tubules of Drosophila melanogaster J. Exp. Biol., January 6, 1999; 202(11): 1561 - 1570. [Abstract] [PDF]
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