Colocalization of glycolytic enzyme activity and KATP channels in basolateral membrane of Necturus enterocytes.
86Rb fluxes through ATP-regulated K+ (KATP) channels in membrane vesicles derived from basolateral membranes of Necturus small intestinal epithelial cells as well as the activity of single KATP channels reconstituted into planar phospholipid bilayers are inhibited by the presence of ADP plus phosphoenolpyruvate in the solution bathing the inner surface of these channels. This inhibition can be prevented by pretreatment of the membranes with 2, 3-butanedione, an irreversible inhibitor of pyruvate kinase (PK) and reversed by the addition of 2-deoxyglucose plus hexokinase. The results of additional studies indicate that PK activity appears to be tightly associated with this membrane fraction. These results, together with considerations of the possible ratio of Na+-K+ pumps to KATP channels in the basolateral membrane, raise the possibility that "cross talk" between those channels and pumps (i.e., the "pump-leak parallelism") may be mediated by local, functionally compartmentalized ATP-to-ADP ratios that differ from those in the bulk cytoplasm.
Dubinsky
W P
WP
Department of Integrative Biology, Pharmacology, and Physiology, University of Texas Medical School, Houston, Texas 77225, USA.
Mayorga-Wark
O
O
Schultz
S G
SG
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D003847:Deoxyglucose / Q000494:pharmacology; D003931:Diacetyl / Q000494:pharmacology; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D006019:Glycolysis / Q000502:physiology*; D006593:Hexokinase / Q000494:pharmacology; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D009337:Necturus / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000494:pharmacology; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D014018:Tissue Distribution
D004338:Drug Combinations; D004791:Enzyme Inhibitors; D008051:Lipid Bilayers; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D000244:Adenosine Diphosphate; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D003847:Deoxyglucose; D006593:Hexokinase; D011770:Pyruvate Kinase; D003931:Diacetyl