Stimulating effect of 6R-tetrahydrobiopterin on Ca2+ channels in neurons


Senior Member
6R-BH4 enhanced N-type Ca2+ channel currents, whereas 6S-BH4, a diastereoisomer of 6R-BH4, had little effect. Neither sodium nitroprusside, a nitric oxide generator, nor L-DOPA, a product of tyrosine hydroxylation, mimicked the effect of 6R-BH4. These findings suggest that 6R-BH4 enhances N-type Ca2+ channel currents in stereospecifically and independently of its cofactor activities as observed in its dopamine releasing action, and raise possibility that 6R-BH4 enhances dopamine release by activating Ca2+ channels.

These Ca2+ channels were in the vagus nerve.

T Shiraki