AGE-DEPENDENCE OF THE LATERAL DIFFUSION-COEFFICIENT OF LIPIDS AND PROTEINS IN THE HEPATOCYTE PLASMA-MEMBRANE OF BN BIRIJHSD RATS AS REVEALED BY THE SMEAR-FRAP TECHNIQUE/

The lateral diffusion coefficients of lipids (D-1) and proteins (D-p) were measured in hepatocyte plasma membranes in freshly prepared liver smears of Brown Norway (BN/BiRijHsd) rats by means of the fluorescenc e recovery after photobleaching (FRAP) method. D-1 was measured after staining with N-4-nitrobenzo-2-oxa-1,3-diazolyl phosphatidylethanolami ne (NBD-PE) in 14 males in four age groups (4.3-30.4 months), and 12 f emales (5.0-31.0 months). D-p, was measured after the development of p eroxide-induced autofluorescence (PIAF) in 16 males in four age groups (4.7-30.8 months) and 15 females in four age groups (4.0-28.1 months) . Highly significant negative, linear age-correlations of 4 (R = -0.97 2 in males, and -0.840 in females, respectively) were found, the avera ge data being 1.39 x 10(-9) cm(2)/s in the young male rats, and only 9 .26 x 10(-10) cm(2)/s in the oldest ones, whereas in females, these tw o extremes were 1.44 x 10-9 and 8.97 x 10(-10) cm(2)/s, respectively. Protein lateral mobility also declined linearly with age; in the male rats it decreased from 2.7 x 10(-10) to 1.8. x 10(-10) cm(2)/s (R = - 0.903), while in the females It decreased from 2.64 x 10(-10) to 2.21x 10(-10) cm(2)/s (R= -0.955) between the youngest and oldest age groups . There were also some characteristic differences in the fractional re coveries (FR%), too. These trends are comparable with those of F344 ra ts studied previously, supporting the conclusion that the changes in t he lateral mobility of plasma membrane proteins and lipids represent i mportant biomarkers of cellular aging also in the BN/BiRijHsd rats. (C ) 1998 Elsevier Science Ireland Ltd. All rights reserved.