Comparison of the lateral diffusion coefficient of hepatocyte plasma membrane proteins in three strains of sensescence accelerated mouse (SAM)

The lateral diffusion coefficients of proteins (D-p) were measured in hepat ocyte plasma membrane in freshly prepared liver smears by means of the fluo rescence recovery after photobleaching (FRAP) method. D-p was measured afte r development of peroxide-induced autofluorescence (PIAF) in a total of 115 senescence accelerated mice (SAM), distributed in three strains. at least five age-groups in each, as follows: (i) SAMR1TA (25 males and 22 females), medium life span (MLS) in months, under specific pathogen free (SPF) condi tions, MLSspf 20.1 and 20.01 respectively, while under conventional conditi ons, MLSDelta pf = 18.9 in average for both sexes; (ii) SAMP6/Ta (18 males and 17 females), MLSspf = 17.1 and 15.3, respectively, and MLScc = 8.1 for both sexes; (iii) SAMP6/Ta (17 males and 16 females), MLSspf = 15.6 and 14. 7, respectively, and MLScc = 10.0 for both sexes. A highly significant nega tive linear age-correlation of D-p (R = 0.975 or higher) was found in each strain, being roughly proportional with the MLScc values. Since the studied mice kept under SPF conditions survived longer, than under conventional co nditions, the actual age-dependent decay rates of D-p values did not differ significantly in two pairs of comparisons (female R1/P6 and female R1/P8), whereas they did in all other possible pairs, including also the normal C5 7BL/6 mice. The main conclusion can be drawn that the D-p of hepatocyte mem branes is a good biomarker of aging and survival also in SAM, as in all oth er inbred and outbred rodents, studied so far. (C) 2001 Elsevier Science ir eland Ltd. All rights reserved.