Anoxia influences the lateral diffusion of a lipid probe in the plasma membrane of isolated cardiac myocytes.

Using the technique of fluorescence photobleaching recovery we have measured the characteristics of lateral diffusion of oleylaminofluorescein (OAF) in the plasma membrane of isolated rat cardiac myocytes under normoxic and anoxic conditions. The normoxic pattern is one of slow diffusion and low recovery (D = 1.8 +/- 0.3 X 10(-10)cm2/s, r = 0.44 +/- 0.059), while under anoxic conditions faster diffusion and higher recovery (D = 2.5 +/- 0.4 X 10(-9)cm2/s, r = 0.58 +/- 0.063) are observed, the change proceeding via an intermediate stage with a yet faster diffusing species (D greater than 2.5 X 10(-9)cm2/s). The process is reversible. We hypothesize that under normoxic conditions the lateral diffusion of OAF is hindered by the division of the cell membrane into a patchwork of more or less isolated domains by lateral and longitudinal barriers of spectrin (7, 13) which are rearranged under anoxic conditions to another pattern which permits the label greater, but still not unrestricted, freedom of movement.