The dependence of the lipid bilayer membrane: buffer partition coefficient of pentobarbitone on pH and lipid composition.
1 The membrane/buffer partition coefficient of [14C]-pentobarbitone has been determined as a function of the lipid composition of bilayer membranes. 2 A new technique based on ultrafiltration gave comparable results to conventional techniques but required less time for equilbration. 3 The membrane/buffer coefficient was independent of pentobarbitone concentration in the range studies. 4 The apparent partition coefficient varied with pH and was a linear function of the degree of dissociation of pentobarbition. 5 Both the charged and uncharged forms of pentobarbitone partitioned into the membrane, the latter to a much greater extent than the former. 6 At low pH the highest partition coefficient observed was in egg phosphatidylcholine bilayer membranes. 7 Incorporation of cholesterol or phosphatidic acid into phosphatidylcholine membranes greatly reduced the partition coefficient. 8 High pressures do not greatly change these partition coefficients.
D002021:Buffers; D002626:Chemistry, Pharmaceutical; D002784:Cholesterol; D006863:Hydrogen-Ion Concentration; D008055:Lipids; D008567:Membranes, Artificial; D010424:Pentobarbital; D010713:Phosphatidylcholines; D011189:Potassium Chloride; D012995:Solubility
D002021:Buffers; D008055:Lipids; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D011189:Potassium Chloride; D002784:Cholesterol; D010424:Pentobarbital