Profile of P-glycoprotein distribution in the rat and its possible influence on the salbutamol intestinal absorption process

J Pharm Sci. 2004 Jun;93(6):1641-8. doi: 10.1002/jps.20071.


The intrinsic absorption of salbutamol in different intestinal segments of the rat was measured and related with the corresponding intestinal P-glycoprotein (P-gp) expression levels. The apparent absorption rate constants (k(a), h(-1)) observed in each fraction by means of the "in situ" rat gut absorption method after perfusion of a 0.29-mM isotonic solution of salbutamol were used as absorption indexes. In a separate series of studies, a semiquantitative analysis of the mRNA expression of P-gp by means of polymerase chain reaction and Western blot with an antibody raised against the P-gp were also performed. The "in situ" k(a) values determined in the different segments (h(-1)) showed that the absorption is not homogeneous along the intestinal tract, that is, 0.499 +/- 0.054 for colon, 0.474 +/- 0.052 for the proximal segment, 0.345 +/- 0.014 for the mean, and 0.330 +/- 0.023 for the distal fraction. Addition of verapamil to the perfusion fluid did provide a better absorption of salbutamol in the distal segment. The analysis of the mRNA expression and levels of P-gp showed that the enzyme content in each section of the intestine was inversely related to salbutamol absorption.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / analysis*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Albuterol / analysis*
  • Albuterol / metabolism*
  • Animals
  • In Vitro Techniques
  • Intestinal Absorption / physiology*
  • Male
  • Rats
  • Rats, Wistar


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Albuterol