One sample antipyrine clearance after 90% partial hepatectomy in the rat

Antipyrine clearance was estimated by a one-sample saliva technique before and after 90% partial hepatectomy in nine rats. For comparison, the hepatic contents of cytochrome P450 and serum alanine amino transaminase activity were determined in vitro. Antipyrine clearance and hepatic cytochrome P450 were reduced according to the reduction in liver weight following hepatectomy. During hepatic regeneration, antipyrine clearance and liver weight increase identically, whereas total cytochrome P450 recovered more slowly, being 71% of initial values at the time when antipyrine clearance and liver weight had recovered. Serum alanine amino transferase activity increased 10-20 times 24 h after hepatectomy, and normalized after 52 h. The hepatic glutathione content per gram liver weight was unchanged during the regeneration, suggesting intact detoxification during hepatic regeneration. This study demonstrates that, although the assessment requires some time, and that a value cannot be attached to a fixed time-point, the one-sample antipyrine saliva clearance is a quantitative in vivo estimate of "functional hepatic mass". The test can easily be applied in animal studies where such a measure is requested.