Lysophosphatidylcholine, a component of atherogenic lipoproteins, induces the change of calcium mobilization via TRPC ion channels in cultured human corporal smooth muscle cells

Hypercholesterolemia is a major risk factor for erectile dysfunction. To understand the mechanism(s) of hypercholesterolemia-induced erectile dysfunction, we studied the effect of lysophosphatidylcholine (LPC) on the membrane conductance of corporal smooth muscle cells. We used cultured human corporal smooth muscle cells. The intracelluar Ca2+ concentration ([Ca2+]i) and the influx of divalent cation was monitored by the ratio of fura-2 fluorescence (F(340/380)) and by the Mn2+-induced quenching rate of fura-2, respectively. The LPC-induced membrane current was characterized by the whole-cell patch-clamp technique and the molecular identity of suspected channels was probed by RT-PCR. LPC (20 microM) induced a statistically significant increase in F(340/380) to 119.9+/-3.9% of initial control (n=6) in corporal smooth muscle cells. The addition of 20 microM LPC accelerated the quenching rate of F360 by 59.5+/-11.8% (n=5). LPC activated nonselective cationic current (ILPC), similar to the known effects of phenylephrine in corporal myocytes. The size of ILPC at -60 mV was -55.3+/-6.3 pA (n=8). The transcript of transient receptor potential channel 6 (TRPC6) was detected in human corporal myocytes. We also found one splicing variant of TRPC6, TRPC6alpha. In conclusion, the present study suggests that the LPC, a major component of oxidized low-density lipoprotiens, increases calcium in corporal smooth muscle cells probably through activation of a TRPC6 channel and the increased [Ca2+]i by LPC via TRP channels is one of mechanisms for hypercholesterolemia-induced erectile dysfunction.