Muscle overwhelms hepatic lactate recycling

A proposed study asks whether restoring muscle could destabilize blood sugar during meals and activity. Its mechanism proposes that restored muscle turns glucose into lactate, a metabolic by-product, faster than the remaining liver can spend energy to convert lactate back into glucose. It predicts rising muscle lactate release, falling liver energy reserves, and liver glucose production that levels off despite available lactate and hormonal signals. A rival model predicts that replacement-derived muscle releases labelled glucose during recovery when tested without a liver. Tracer studies, lactate-turnover tests and liver energy spectroscopy could distinguish these explanations before ex vivo or animal studies assess relevance to older recipients.