Effect of cholesterol and temperature perturbations on membrane hydrolases and transport of calcium and glucose in guinea pig brush border membrane vesicles.
The function of membrane cholesterol (chol) in the regulation of membrane-bound hydrolases and transport proteins has been investigated in chol-enriched membranes of guinea pig intestinal brush borders. Chol-enrichment is accomplished by non-invasive means i.e., dietary manipulation by high-chol diet feeding. Activities of sucrase, lactase and maltase enzyme systems, Na+-dependent and -independent glucose transport and calcium uptake are found to be greatly inhibited by chol both at 22 degrees C and 37 degrees C. Glucose and calcium uptake in native membranes are found to be temperature sensitive processes and produce nonlinear Arrhenius plots with a transition temperature around 22 degrees C. The discontinuity in the Arrhenius expression is lost in chol enriched membranes which is interpreted as the increase in microviscosity imparted by chol in the bulk lipid phase environment where these proteins operate.
Minocha
R
R
Department of Experimental Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Sanyal
S N
SN
Wali
A
A
Gumbhir
K
K
Majumdar
S
S
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000493:pharmacokinetics*; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology; D005947:Glucose / Q000493:pharmacokinetics*; D006168:Guinea Pigs; D006867:Hydrolases / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism*; D013696:Temperature
D004041:Dietary Fats; D008563:Membrane Lipids; D002784:Cholesterol; D006867:Hydrolases; D005947:Glucose; D002118:Calcium