Fig. 5.
Lack of permeability to small osmolytes in M1, M23, and Mz-expressing oocytes. a The L p of oocytes expressing M1, M23, and Mz as well as non-injected oocytes was determined with different osmolytes; mannitol, urea, glycerol, and formamide (20 mOsm of each). The L p obtained with urea, glycerol, and formamide was plotted relative to that obtained with mannitol for each oocyte (reflection coefficient, σ). The reflection coefficients for oocytes expressing M1, M23, or Mz were not significantly different from that of the non-injected oocytes (n = 4 of each isoform and n = 3 for the non-injected oocytes). b Oocytes expressing M1, M23, and Mz as well as non-injected oocytes were exposed to test solution containing different osmolytes; mannitol, urea, glycerol, and formamide (20 mOsm of each) in addition to trace amounts of the [14C]-labeled osmolyte. The data are presented as the average uptake of four experiments performed in pentaplicate, with no significant difference between oocytes expressing the three isoforms and the non-injected oocytes