Effects of local anesthetics on membrane properties I. Changes in the fluidity of phospholipid bilayers

D. Papahadjopoulos, K. Jacobson, G. Poste, G. Shepherd

Research output: Contribution to journalArticlepeer-review

283 Scopus citations


The effect of the local anesthetic dibucaine on the solid to liquid-crystalline phase transition in phospholipid vesicles was studied by calorimetry and fluorescence polarization. The partition coefficient (> 3000) of dibucaine in the membranes of vesicles prepared from acidic phospholipids was more than 20 times higher than in neutral phospholipid membranes under the same conditions. Calorimetric measurements on vesicles prepared form acidic phospholipids (bovine brain phosphatidylserine; dipalmitoylphosphatidylglycerol) showed that dibucaine (1 · 10-4 M) produced a significant reduction in the gel-liquid crystalline transition temperature (Tc). This fluidizing effect of dibucaine on acidic phospholipid membranes was even more marked in the presence of Ca2+. In contrast, dibucaine at the same concentration did not alter the Tc of neutral phospholipids (dipalmitoylphosphatidylcholine). Significant increase in the fluidity of neutral phospholipid membranes occurred only at higher dibucaine concentrations (2 · 10-3 M. Measurements of the fluorescence polarization and lifetime of the probe, 1,6-diphenylhexatriene, in acidic phospholipid vesicles revealed that dibucaine (1 · 10-4 M caused an increase in the probe rotation rate indicating an increase in the fluidity of the phospholipid membranes. A good correlation was obtained between fluorescence polarization data on dibucaine-induced changes in membrane fluidity and calorimetric measurements on vesicles of the same type.

Original languageEnglish (US)
Pages (from-to)504-519
Number of pages16
JournalBBA - Biomembranes
Issue number4
StatePublished - Jul 18 1975
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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