Volume- and temperature-dependent permeabilities in isolated rat liver cells

Area of Science:

• Cellular Physiology
• Membrane Transport
• Ion Channels

Background:

• Understanding ion transport in hepatocytes is crucial for cellular homeostasis.
• Cooling and rewarming can significantly impact cell volume and membrane permeability.

Purpose of the Study:

• To investigate the effects of cooling and rewarming on ion fluxes and membrane permeability in isolated rat hepatocytes.
• To elucidate the mechanisms underlying transient changes in potassium (K) and sodium (Na) permeability.

Main Methods:

• Isolated rat hepatocytes were incubated at 1°C and then 38°C.
• K and Na contents and fluxes were measured.
• Cell volume changes were induced by osmotic shock.
• Inhibitors of Ca-activated K channels and divalent ionophores were used.

Main Results:

• Cooling induced cell swelling and altered K and Na gradients.
• Rewarming caused transient paradoxical movements of K and Na, attributed to increased membrane permeabilities.
• These permeability changes were volume-dependent and not sensitive to Ca channel blockers or ionophores, suggesting a lack of Ca-sensitive K channels.

Conclusions:

• Transient changes in hepatocyte K and Na permeability during rewarming are a consequence of cell swelling induced by cooling.
• These volume-dependent permeabilities are suppressed at low temperatures and revealed upon rewarming.
• Rat hepatocytes appear to lack Ca-sensitive K channels.