Insulin increases the density of potassium channels in white adipocytes: possible role in adipogenesis

Abstract

We studied the potassium currents in white adipocytes obtained by culturing preadipocytes from rat epididymal tissue, both with insulin (WA i ) and without insulin (WA o ), in order to test the role of insulin in the development of voltage-gated potassium channels (K v ) during adipogenesis. Occasionally, very small potassium currents (I K,V ) were present in preadipocytes; however these currents were measured in all differentiated cells (adipocytes). WA i exhibited greater macroscopic potassium currents than WA o with no apparent differences in kinetics or voltage dependence. The current density (pA/µm 2 ) calculated in WA i was higher than in WA o . Currents were blocked by millimolar concentrations of tetrethylamonium (TEA). The effect of insulin on adipogenesis, both with and without TEA, was analysed. Four days without insulin and three days with insulin were necessary to increase the total number of cells in culture by 2·5-fold. Insulin increased the number of differentiated cells by 73·5%. Cell proliferation and differentiation were inhibited by TEA. Proliferation was affected only by high concentration of TEA. Inhibition of differentiation was dose dependent, with the concentration necessary for half-block similar to the IC 50 values to block potassium channels. These results suggest that insulin increases the density of K v and that these channels may be necessary for the normal growth of white adipocytes in culture.

Visceral Periadventitial Adipose Tissue Regulates Arterial Tone of Mesenteric Arteries

“…22,23 In contrast to smooth muscle cells, K v channels in adipocytes are rapidly-inactivating, sensitive to TEA, 24 -26 and relatively resistant to 4-AP. [27][28][29] Ba 2ϩ -sensitive inward rectifying K ϩ have not been detected in adipocytes. In addition, we found that the intracellular membrane potential was more negative in smooth muscle cells of (ϩ) fat rings compared with (Ϫ) fat rings, a difference that was abolished by 4-AP.…”

An Exploratory Study of the Association between KCNB1 rs1051295 and Type 2 Diabetes and Its Related Traits in Chinese Han Population

“…We demonstrated the mean HDL-C (TT: 1.65 versus CC: 1.67, P  = 0.47) was lower and LDL-C (TT: 2.72 versus CC: 2.63, P  = 0.46) was higher in the population with a TT genotype than those with a CC genotype, which may provide some clues for future investigation on how rs1051295 genotype TT might influence fat metabolism. In support of a role of Kv channels in adipocyte metabolism, Kv channel activity has been recorded in human adipocytes [26], which responded to insulin by increasing channel density [27]. However, the specific Kv isoform or its downstream actions in adipocytes have not been critically assessed, thus requiring much further study.…”

Voltage-gated K+ channels in adipogenic differentiation of bone marrow-derived human mesenchymal stem cells

“…In addition, TEA has been shown to inhibit the differentiation of white adipose cells from preadipocytes, suggesting the involvement of Kv channels in adipogenesis in these cells, although specific K + channel subtypes were not defined [9] . Therefore, expression of Kv channels in undifferentiated cells and alterations in Kv channels during differentiation may somehow be involved in the differentiation process.…”

“…A number of factors are critical for differentiation of hMSCs along a particular lineage, including cell density, mechanical forces, and multifactorial stimulation with specific nutrients [3][4][5][6][7] . For example, insulin, insulin-like growth factor I, glucocorticoids, and other growth hormones are known to be essential for adipogenic differentiation in vitro [2,4,[7][8][9] . Voltage-gated K + (Kv) channels are important in maintain-ing cellular excitability in neurons and muscle cells.…”