Pulsatile, synchronous basal insulin and glucagon secretion in man

Area of Science:

• Endocrinology
• Metabolic Physiology
• Cellular Signaling

Background:

• Hormonal regulation of glucose homeostasis is complex.
• Pulsatile secretion of hormones is increasingly recognized as important.
• The interplay between insulin and glucagon dynamics is not fully understood.

Purpose of the Study:

• To investigate the pulsatile secretion patterns of plasma insulin and glucagon in normal subjects.
• To determine the relationship and temporal dynamics between insulin and glucagon oscillations.
• To explore the potential physiological significance of synchronous insulin and glucagon pulses.

Main Methods:

• Continuous blood sampling at 1-minute intervals for 45-120 minutes in 28 normal subjects.
• Autocorrelation analysis to detect regular cycles in plasma insulin, glucagon, and glucose.
• Cross-correlation analysis to assess temporal relationships and delays between hormonal fluctuations.

Main Results:

• Regular plasma insulin cycles (mean period 10.7 min) were detected in all subjects.
• Associated plasma glucagon and glucose cycles were observed, with mean periods of 13.1 and 13.7 min respectively.
• A significant positive correlation between insulin and glucagon cycle amplitudes was found (r=0.23, P<0.05), with a 2-minute delay in glucagon changes after insulin.
• No comparable oscillations were detected for plasma pancreatic polypeptide.

Conclusions:

• Synchronous pulsatile secretion of insulin and glucagon occurs in normal individuals.
• This pulsatility may serve to modulate hepatic glucose production while allowing adequate peripheral insulin action.
• A potential pacemaker mechanism involving A-B intercellular connections could drive this synchronized hormonal release.