Fig 2: TRPC5 expression identified in human cavernosal tissue and penile arteries. Left panels show representative immunofluorescence images showing TRPC5 detection (green fluorescence) in cryosections of the corpus cavernosum (HCC) and penile resistance arteries (HPRAs) from individuals without erectile dysfunction (NoED, panels (A,C)) and patients with erectile dysfunction (ED, panels (B,D)). Nuclei are counterstained in blue. Panel (E) shows the quantification of TRPC5 protein levels in human cavernosal homogenates from NoED subjects and ED patients. Data are expressed as individual values and mean ± S.E.M. of the nanograms of TRPC5 normalized to the tissue’s protein content. n indicates number of subjects. No significant differences were observed.

Fig 3: TRPC5 inhibitor outperforms TRPC3 and TRPC4 inhibitors in relaxing aged rat corpus cavernosum. Representative tracings of relaxations induced by TRPC5 inhibitor (AC1903, 0.1 to 30 µM) in corpus cavernosum (RCC) strips from young adult (3-month-old, 3 M, panel (A)) and aged (20-month-old, 20 M, panel (D)) rats contracted. Panels (B,E) present concentration–response relaxation curves for vehicle (DMSO 0.001 to 0.3%), the TRPC3 inhibitor (Pyr3), the TRPC4 inhibitor (ML204), and AC1903 in RCC from 3 M rats (B) and 20 M rats (E). The area under the curve (AUC) of the percentage of relaxation induced by these inhibitors in RCC from 3 M and 20 M rats is represented in (C,F), respectively. Phenylephrine (PE, 1–10 µM) was used to precontract all tissues. Data are presented as mean ± S.E.M of the relaxation percentage (B,E) and as individual values and mean ± S.D. of the AUC of relaxation (C,F). n indicates the number of animals from whom the tissues were collected. ** p < 0.01, *** p < 0.001 vs. vehicle, and †† p < 0.01, ††† p < 0.001 vs. Pyr3 by a two-factors ANOVA (B,E) or by one-factor ANOVA followed by Holm–Sidak’s multiple comparisons test (C,F).

Fig 4: TRPC5 inhibition promotes effective relaxations in human penile vascular tissue. Upper panels show relaxation responses to increasing concentrations (0.1 to 30 µM) of the TRPC3 inhibitor (Pyr3), or the TRPC5 inhibitor AC1903 in human corpus cavernosum (HCC) from organ donors without erectile dysfunction (NoED, panel (A)) and from patients with erectile dysfunction (ED, panel (B)). The same responses were evaluated in human penile resistance arteries (HPRAs) from NoED subjects (C) and in subjects with ED (D). HCC strips were precontracted with phenylephrine (PE, 1–10 µM), while norepinephrine (NE, 1–10 µM) was used to precontract HPRA segments. Data are expressed as mean ± S.E.M of the relaxation percentage. n represents patients’ number from whom the tissues were obtained. ** p < 0.01 and *** p < 0.001 vs. Pyr3 by a two-factors ANOVA.

Fig 5: Inhibition of TRPC5 increased the efficacy of PDE5 inhibition in relaxing the penile vasculature of patients with ED. Panel (A,B) illustrates the effect of vehicle (DMSO 0.3%) and theTRPC5 inhibitor (AC1903, 3 µM) on endothelial relaxations induced by the PDE5 inhibitor sildenafil (1 nM to 10 µM) in the HCC (A) and in penile resistance arteries (HPRAs) from ED patients (B). Phenylephrine (PE, 1–10 µM) was used to precontract HCC strips while HPRA segments were precontracted with norepinephrine (NE, 1–10 µM). Data are presented as mean ± S.E.M of the relaxation percentage. The number of patients from whom tissues were obtained is denoted by n. *** p < 0.001 vs. vehicle by a two-factors ANOVA.