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Thiopental binding to human serum albumin in the presence of halothane
Author(s) -
Bücn H. P.,
Altmayer P.,
Büch U.
Publication year - 1990
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1990.tb03037.x
Subject(s) - medicine , halothane , albumin , serum albumin , human albumin , anesthesia , pharmacology
In vitro thiopental binding (substrate concentration 0.04 · 10 ‐3 M=10 μg/ml) to 1% human serum albumin (HSA) increased significantly from 40.2% (=control) to 47.3% in the presence of 1.18 · 10 ‐3 M = 2.84 vol% halothane. A 4‐fold higher halothane concentration (4.71 · 10 ‐3 M) had an even greater effect with an increase in the thiopental fraction bound to 55.5%. With a constant HSA concentration (1% or 5%) and thiopental concentrations in the range 0.01–1.5 · 10 ‐3 M or 0.01–0.38 · 10 ‐3 M, respectively, the halothane effect ( increase in thiopental binding) was always evident, as well as in other experiments with constant thiopental concentration (0.04 · 10 ‐3 M) and variation in the HSA concentration (0.5 – 10%). Two classes of binding sites for thiopental were apparent at the HSA molecule. In the control experiments the following binding parameters were found: n 1 =0.01, k 1 = 181 · 10 3 M ‐1 ; n 2 =45.73, k 2 =0.08 · 10 3 M ‐1 , K=5.47 · 10 3 M ‐1 . In the presence of halothane the binding parameters changed as follows: n 1 = 0.14, k 1 =29.4 · 10 3 M ‐1 ; n 2 = 11.68, k 2 =0.42 · 10 3 M ‐1 , K=9.02 · 10 3 M ‐1