Uptake and release of immunoreactive insulin in coronary circulation in man: studies at rest, during exercise, and during glucose and insulin infusions.

Significant uptake and release of immunoreactive insulin by the heart have been observed in man, and this is related to plasma insulin levels. Exercise and the fed state appear to affect the myocardial handling of insulin. The findings could not be related to myocardial carbohydrate metabolism, but could, during exercise, be related to myocardial lipid metabolism.