Potassium channels in basolateral membrane vesicles from necturus enterocytes: stretch and ATP sensitivity

Area of Science:

• Cell Biology
• Physiology
• Membrane Transport

Background:

• Basolateral membrane vesicles from Necturus maculosus small intestinal cells exhibit ATP-inhibitable K(+) channels.
• These channels show volume regulatory responses similar to intact tissue exposed to anisotonic solutions.

Purpose of the Study:

• To investigate the effect of glucose and alanine on K(+) channel activity in intestinal cell vesicles.
• To determine the mechanism by which cell swelling affects ATP-inhibitable K(+) channels.

Main Methods:

• Utilized vesicles from Necturus maculosus small intestinal basolateral membrane.
• Exposed vesicles to isotonic and anisotonic solutions with varying solutes (glucose, alanine).
• Measured K(+) channel activity and ATP inhibition.

Main Results:

• Increased K(+) channel activity was observed in vesicles exposed to isotonic solutions containing glucose or alanine.
• Cell swelling, induced by hypotonic or isotonic solutions with solutes, reduced ATP inhibition of channel activity.
• This reduction in ATP inhibition was not solely due to intravesicular ATP dilution.

Conclusions:

• ATP-sensitive, stretch-activated K(+) channels are likely responsible for increased basolateral membrane K(+) conductance in Necturus small intestinal cells upon addition of sugars or amino acids.
• Increased cell volume and subsequent membrane stretch decrease the sensitivity of these K(+) channels to ATP inhibition.