University of Kentucky
Effects of Ouabain on Intestinal Sodium Reabsorption in Procambarus clarkii
Institution
University of Kentucky
Faculty Advisor/ Mentor
Jeffrey Osborn
Abstract
Procambarus clarkii, or swamp crayfish, experience daily fluctuations in salinity, and are known to both osmoregulate, as well as osmoconform. In a previous experiment, I found that the lower gut of the decapod P.clarkii will reabsorb normal crayfish solution (~200mM NaCl) at an average of 28.78ul/min. I hypothesized that saturating the outside of the GI track with ouabain will decrease reabsorption rate. Ouabain binds to and inhibits Na+/K+ ATPase. The inhibition of the Na+/K+ pumps will stop the transfer of Na+ out of the intestinal lumen, in turn stopping reabsorption. Since Na+/K+ ATPase are mostly located on the basolateral membrane, ouabain is administered on the outside to effectively block the Na+ pumps. Large P.clarkii (25-30g) were obtained from Atchafalay Biological and allowed to acclimate for 2 weeks. Crayfish were sedated in an ice water bath prior to experiment. Polyethelyne tubing was inserted into the anterior opening of the GI tract for perfusion, as well as the anus for collection of perfusate. Five different concentrations of ouabain saturated the outside of the GI track for 20 minutes: [10] ^(- 9) M, [10] ^(-7) M, [10] ^(-5) M,and [10]^(-3) M. Simultaneously a constant flow of normal crayfish solution was perfused through the GI track and the perfusate was collected. Results did not show a uniform decrease or increase of the reabsorption rates. I concluded that the potential osmoregulatory function of the intestine of the freshwater crayfish P.clarkii is not regulated by Na+/K+ ATPase. Future experiments will be carried out to investigate a potential role for osmoregulation in the intestine of P.clarkii.
Effects of Ouabain on Intestinal Sodium Reabsorption in Procambarus clarkii
Procambarus clarkii, or swamp crayfish, experience daily fluctuations in salinity, and are known to both osmoregulate, as well as osmoconform. In a previous experiment, I found that the lower gut of the decapod P.clarkii will reabsorb normal crayfish solution (~200mM NaCl) at an average of 28.78ul/min. I hypothesized that saturating the outside of the GI track with ouabain will decrease reabsorption rate. Ouabain binds to and inhibits Na+/K+ ATPase. The inhibition of the Na+/K+ pumps will stop the transfer of Na+ out of the intestinal lumen, in turn stopping reabsorption. Since Na+/K+ ATPase are mostly located on the basolateral membrane, ouabain is administered on the outside to effectively block the Na+ pumps. Large P.clarkii (25-30g) were obtained from Atchafalay Biological and allowed to acclimate for 2 weeks. Crayfish were sedated in an ice water bath prior to experiment. Polyethelyne tubing was inserted into the anterior opening of the GI tract for perfusion, as well as the anus for collection of perfusate. Five different concentrations of ouabain saturated the outside of the GI track for 20 minutes: [10] ^(- 9) M, [10] ^(-7) M, [10] ^(-5) M,and [10]^(-3) M. Simultaneously a constant flow of normal crayfish solution was perfused through the GI track and the perfusate was collected. Results did not show a uniform decrease or increase of the reabsorption rates. I concluded that the potential osmoregulatory function of the intestine of the freshwater crayfish P.clarkii is not regulated by Na+/K+ ATPase. Future experiments will be carried out to investigate a potential role for osmoregulation in the intestine of P.clarkii.