Energetics of Potassium Ion Transport in Aplysia Gut

Abstract

Basolateral membranes of Aplysia californica foregut epithelia contain an ATP-dependent Na + /K + transporter (Na + /K + pump or Na + /K +-ATPase). This Na + /K + pump accounts for both the intracellular Na + electrochemical potential () being less than the extracelluar Na + and the intracellular K + being more than the extracellular K +. Also, K + channel activity resides in both luminal and basolateral membranes of the Aplysia foregut epithelial cells. Increased activity of the Na + /K + pump, coupled to luminal and basolateral membrane depolarization altered the K + transport energetics across the basolateral membrane to a greater extent than the alteration in K + transport energetics across the luminal membrane. These results suggest that K + transport, either into or out of the Aplysia foregut epithelial cells, is rate-limiting at the basolateral membrane.

Ultrastructural, histochemical and cytochemical characterization of intestinal epithelial cells in Aplysia depilans (Gastropoda, Opisthobranchia)

“…Although ultrastructural studies of intestinal cells have been performed in some species of pulmonate gastropods (Boer and Kits 1990; Triebskorn and Künast 1990; Franchini and Ottaviani 1992; Leal‐Zanchet 2002), such studies are scarcer in prosobranchs (Bush 1988; Pfeifer 1992) and non‐existent in opisthobranchs. However, the intestinal epithelium of A. californica has been used for physiological research (Gerencser 2000; Gerencser et al . 2002; Keeton et al .…”