Effects of glucosamine on Ca2+ signaling and K+ channel currents in T lymphocytes

Suh, Eun Young; Pang, Bo; Kim, Sung Joon; Kim, Woo Kyung

Abstract

BACKGROUND/AIMS
Glucosamine is widely taken as a functional food, and some studies reported its anti-inflammatory effects. K+ channels and intracellular signal play important roles in the activation of immune cells such as T lymphocytes. Therefore we aimed to examine the effects of glucosamine on the cell physiological parameters.
METHODS
In Jurkat-T lymphocytes, intracellular [Ca2+] ([Ca2+]i) was measured using fura-2 fluorimetry, and voltage-gated K+ current (I(Kv)) was measured using whole-cell clamp technique. Ca2+-activated K+ current (I(Kca)) was measured in HEK293 cells over expressing SK4 using inside-out patch clamp technique.
RESULTS
An acute application of glucosamine (0.5 mM) affected neither the increase in [Ca2+]i induced by CD3 stimulation (anti-CD3 Ab, 5 microgram/mL) nor the I(Kv) in Jurkat-T cells. A chronic stimulation of with anti-CD3 Ab (5 microgram/mL, 24~36 hr) largely increased the amplitude of IKv. However, the combined treatment with glucosamine (0.1 mM) did not block the increase of I(Kv). The I(KCa) in SK4-overexpressing cells was slightly decreased by glucosamine (0.5 mM).
CONCLUSIONS
While glucosamine had a minor inhibitory effect on SK4 K+ channels, the anti-inflammatory effects of glucosamine could not be explained by the effects on the Ca2+ signaling in T lymphocytes.