Effect of hypertonicity on the increase in basolateral conductance of Necturus small intestine in response to Na⁺-sugar cotransport

Exposure of Necturus small intestine to a galactose-containing perfusate that is 20% hypertonic compared to the galactose-free (control) perfusate results in a rapid depolarization of the electrical potential difference across the apical membrane, ψ^mc, and a decrease in the ratio of the resistance of the apical membrane to that of the basolateral membrane, (r^m/r^s); however, the slow repolarization of ψ^mc and increase in (r^m/r^s), observed under isotonic conditions, is blocked. These findings are consistent with the notion that the increase in the conductance of the basolateral membrane in response to Na⁺-coupled sugar (or amino acid) transport across the apical membrane may be a 'volume regulatory response' to cell swelling.