Article date: September 1977
By: K.W. MILLER, S‐C. T. YU in Volume 61, Issue 1, pages 57-63
The membrane/buffer partition coefficient of [14C]‐pentobarbitone has been determined as a function of the lipid composition of bilayer membranes.
A new technique based on ultrafiltration gave comparable results to conventional techniques but required less time for equilibration.
The membrane/buffer coefficient was independent of pentobarbitone concentration in the range studied.
The apparent partition coefficient varied with pH and was a linear function of the degree of dissociation of pentobarbitone.
Both the charged and uncharged forms of pentobarbitone partitioned into the membrane, the latter to a much greater extent than the former.
At low pH the highest partition coefficient observed was in egg phosphatidylcholine bilayer membranes.
Incorporation of cholesterol or phosphatidic acid into phosphatidylcholine membranes greatly reduced the partition coefficient.
High pressures do not greatly change these partition coefficients.
The membrane/buffer partition coefficient of [14C]‐pentobarbitone has been determined as a function of the lipid composition of bilayer membranes.
A new technique based on ultrafiltration gave comparable results to conventional techniques but required less time for equilibration.
The membrane/buffer coefficient was independent of pentobarbitone concentration in the range studied.
The apparent partition coefficient varied with pH and was a linear function of the degree of dissociation of pentobarbitone.
Both the charged and uncharged forms of pentobarbitone partitioned into the membrane, the latter to a much greater extent than the former.
At low pH the highest partition coefficient observed was in egg phosphatidylcholine bilayer membranes.
Incorporation of cholesterol or phosphatidic acid into phosphatidylcholine membranes greatly reduced the partition coefficient.
High pressures do not greatly change these partition coefficients.
DOI: 10.1111/j.1476-5381.1977.tb09739.x
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