Differential and interactive effects of calcium channel blockers and cholesterol content of the diet on jejunal uptake of lipids in rabbits

The present study was undertaken to determine the effects of two classes of calcium channel blockers (CCB), nisoldipine (N) and verapamil (V), on the jejunal uptake of lipids in rabbits. The uptake of cholesterol and long‐chain fatty acids into rabbit jejunum was examined after 6 and 36 min of exposure to N or Vin vitro (“acute” studies), and after 3‐wk feeding of N or V (“chronic” studies). Animals were fed either a low (0.08%) cholesterol diet (LCD) or a high (2.8%) cholesterol diet (HCD), with or without N or V added. Acutein vitro exposure of the jejunum to N or V did not affect the uptake of cholesterol or palmitic acid in rabbits fed LCD or HCD. The effect of N or V feeding depended upon the cholesterol content of the diet; adding N or V to LCD increased cholesterol uptake while adding N or V to HCD enhanced or lowered cholesterol uptake, respectively. Both N and V increased the uptake of stearic acid in LCD. N in HCD had no effect on fatty acid uptake, whereas V lowered the uptake of stearic and linoleic acids and increased the uptake of oleic acid. These changes in lipid uptake were not due to variation in the animals' food intake, body weight gain, or intestinal mucosal surface area. The chronic administration of N or V results in an intestinal adaptive process that alters the jejunal uptake of lipids, the direction of which is influenced by the class of CCB, and by the cholesterol content of the diet. The serum lipid‐lowering effect of administering N to rabbits fed HCD demonstrated previously is unlikely to be the result of a decrease in intestinal lipid uptake.