Fluid-phase endocytosis by isolated rat adipocytes

Area of Science:

• Cell Biology
• Biochemistry

Background:

• Adipocytes play a crucial role in glucose metabolism and energy storage.
• Understanding endocytosis and exocytosis in adipocytes is vital for metabolic research.

Purpose of the Study:

• To develop and validate an assay for measuring fluid-phase endocytosis and exocytosis in isolated rat adipocytes.
• To investigate the effect of insulin on these cellular processes.

Main Methods:

• Utilized radiolabeled sucrose as a marker for fluid-phase uptake and release.
• Measured sucrose uptake and release rates in isolated rat adipocytes over time.
• Assessed the impact of insulin on sucrose transport and [14C]EDTA uptake.

Main Results:

• Adipocytes exhibit linear sucrose uptake for at least 1.5 hours.
• A portion of pinocytosed sucrose is rapidly released via exocytosis (half-time ~20 minutes).
• Insulin significantly increased sucrose uptake by 31% (P<0.01) but did not affect sucrose release.

Conclusions:

• The developed assay effectively quantifies fluid-phase endocytosis and exocytosis in adipocytes.
• Insulin has a modest, statistically significant stimulatory effect on fluid-phase endocytosis in adipocytes.
• Insulin does not significantly influence the rate of fluid-phase exocytosis in these cells.