Insulin and substrate exchange in the forearm during prolonged forearm work

Abstract

Forearm exchange of insulin and uptake of oxygen, glucose and free fatty acids (FFA) were studied during 120 min forearm work in six healthy male volunteers. At rest the arterial-deep venous difference of insulin was zero. At the onset of work release of insulin occurred, which continued at constant rate throughout the work despite unaltered arterial insulin concentration. Extractions of oxygen, glucose and FFA were of similar magnitudes at 120 as at 15 min work, while lactate release decreased with time. It is concluded that (1) a significant insulin release from muscle tissue or its vascular bed occurs and continues at undiminished rate during prolonged work, (2) a substantial amount of insulin must be bound in the tissue, unless local synthesis takes place and (3) despite this loss of insulin from the forearm no major change in glucose and FFA extraction occurs with duration of work.

Key Words:

• FFA
• forearm work
• glucose uptake
• insulin exchange