Time dependence of the proton relaxation times of regenerating rat liver.

The proton longitudinal relaxation time of regenerating rat liver has been found to increase during the first 24 hours after hepatectomy and to drop back to normal in the following hours. The decreased relaxation rate may be related to the increase of the water mobility due to the expansion of the intercellular spaces during the massive proliferation of the first day, or to the increased cell hydration which is known to occur during active cell proliferation. Equations have been derived for the proliferation process, and the competing inhibition process, active from the 24th hour, which can quantitatively account for the proton relaxation behaviour.