[Insulin oscillations--clinically important rhythm. Antidiabetics should increase the pulsative component of the insulin release].

The concentration of circulating insulin oscillates with periods of 3-6 min due to pulsatile release of the hormone from the pancreas. Pulsatile insulin secretion from the individual * cell is driven by slow cycles of Ca2+ elevation due to periodic depolarisation. The Ca2+ oscillations of individual * cells in the islets of Langerhans are entrained into a common rhythm by gap junctional coupling and diffusible factors. Autonomic ganglia coordinate the oscillatory activity of the million islets in the pancreas. ATP binding to purinoceptors causes pronounced Ca2+ spikes that are important for synchronizing the *-cells within and among islets in the pancreas. Inhibition of purinergic P2Y1 receptors selectively abolishes pulsatile insulin release without reducing the average rate of secretion. The insulin oscillations are particularly important for the liver. This organ is also exposed to oscillating levels of glucagon. The latter oscillations are in opposite phase allowing maximal exposure to insulin when the glucagon concentration is at minimum.