Emerging Concepts in Ion Channel Biophysics

Emerging Concepts in Ion Channel Biophysics

Poster Abstracts

32-POS Board 32 Age-related Activity and Expression of Voltage-dependent Calcium Channels during Postnatal Development of Pancreatic Beta Cells of Rats Neivys García Delgado , Myrian Velasco Torres, Carmen Sánchez Soto, Marcia Hiriart Urdanivia. Instituto de Fisiología Celular, UNAM, Ciudad de México, Mexico. Pancreatic beta cell acquires functional maturity during the first month of life, allowing them to secrete robust insulin secretion in response to increases in extracellular glucose concentration. Near the ablactating period (20 days) we have observed a period of physiological insulin resistance. We are interested in possible changes in ion channel activity during maturating stages. Within the voltage-dependent calcium channels in beta cells, low-voltage-activated (LVA) have been poorly studied. However, it is well accepted that high-voltage-activated (HVA), specifically type L channels are responsible for the increase of intracellular calcium concentration and insulin exocytosis. In this work, we analyzed the changes in the expression and activity of calcium channels during the postnatal development of the rat pancreatic beta cell. Beta cells were obtained from pancreas of neonatal, 20 days and two months male old Wistar rats. Electrophysiological recordings were performed using whole-cell voltage clamp technique. Channels expression was visualized by immunofluorescence. The detection percentage of LVA current increased with the age of the animal. Peak currents of LVA and HVA channels were close to -10 mV and +20 mV, respectively. Maximum amplitude of both currents were higher in the adult cells. Immunocytochemistry revealed the presence of α1G, α1H and α1I subunits of LVA channels at all ages. The Cav 3.1 subunit was most expressed. Adult beta cells expressed more Cav 3.1 and Cav 3.2 than 20 days cells. Together these results show that calcium channels have a differential expression and activity during rat pancreatic beta cell maturation, which is related to insulin secretion.

This work was supported partially by DGAPA PAPIIT-UNAM Grant IN210817, CONACyT Grant CB-253222 and C3 DGAPA PAPIIT Grant IV100116.

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