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Pregnenolone sulphate-independent inhibition of TRPM3 channels by progesterone.

Majeed Y, Tumova S, Green BL, Seymour VA, Woods DM, Agarwal AK, Naylor J, Jiang S, Picton HM, Porter KE, O'Regan DJ, Muraki K, Fishwick CW, Beech DJ - Cell Calcium (2011)

Bottom Line: Progesterone metabolites and 17β-oestradiol were also inhibitory but the effects were relatively small.Corticosteroids lacked effect.Relevance of TRPM3 or the progesterone effect to ovarian cells, which have been suggested to express TRPM3, was not identified.

View Article: PubMed Central - PubMed

Affiliation: Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK.

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Progesterone resistant ionic currents in granulosa cells. Data were generated by whole-cell patch-clamp performed in freshly isolated bovine granulosa cells. (a) Example time-series plot showing the effect of 10 μM prog on current evoked by 100 μM PregS. 100 μM lanthanum (La3+) was applied at the end as a quality control for the whole-cell recording. (b) For the experiment of (a), I–Vs in the presence of 100 μM PregS, with 10 μM prog (+10 prog), or 100 μM La3+. (c) As for (a), but mean currents normalised to pre-prog amplitudes (n = 4). (d) Example time-series plot showing the effect of 10 μM prog on current evoked by 10 μM PregS. (e) For the experiment of (d), I–Vs in the presence of 10 μM PregS, or with 10 μM prog (+10 prog). (f) As for (d), but mean currents normalised to pre-prog amplitudes (n = 5).
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fig0055: Progesterone resistant ionic currents in granulosa cells. Data were generated by whole-cell patch-clamp performed in freshly isolated bovine granulosa cells. (a) Example time-series plot showing the effect of 10 μM prog on current evoked by 100 μM PregS. 100 μM lanthanum (La3+) was applied at the end as a quality control for the whole-cell recording. (b) For the experiment of (a), I–Vs in the presence of 100 μM PregS, with 10 μM prog (+10 prog), or 100 μM La3+. (c) As for (a), but mean currents normalised to pre-prog amplitudes (n = 4). (d) Example time-series plot showing the effect of 10 μM prog on current evoked by 10 μM PregS. (e) For the experiment of (d), I–Vs in the presence of 10 μM PregS, or with 10 μM prog (+10 prog). (f) As for (d), but mean currents normalised to pre-prog amplitudes (n = 5).

Mentions: We speculated that progesterone regulation of TRPM3 might also be relevant to the female reproductive system where progesterone has potent biological effects. A previous report suggested TRPM3 expression in human ovaries [9]. There were no reports of functional TRPM3 channels in this context and so we investigated if functional channels exist by making whole-cell patch-clamp recordings from granulosa cells freshly isolated from bovine ovarian follicles [14]. In K+-current recording solutions, A-type K+-current was observed (Supplementary Fig. VI), as expected for this cell type [18]. In TRPM3 recording solutions, pregnenolone sulphate evoked large ionic currents but only after delays of several minutes (Fig. 11a, d), which is not expected for TRPM3 (cf.Fig. 3a). The I–Vs of the evoked currents were almost linear (Fig. 11b, e), which is not standard for TRPM3 (cf.Fig. 3b), although has been observed in some recordings [19]. Progesterone did not inhibit the currents evoked by pregnenolone sulphate (Fig. 11a–f). The data suggest that granulosa cells contain ionic currents that are stimulated by pregnenolone sulphate but that these currents may not be mediated by TRPM3 and are not inhibited by progesterone.


Pregnenolone sulphate-independent inhibition of TRPM3 channels by progesterone.

Majeed Y, Tumova S, Green BL, Seymour VA, Woods DM, Agarwal AK, Naylor J, Jiang S, Picton HM, Porter KE, O'Regan DJ, Muraki K, Fishwick CW, Beech DJ - Cell Calcium (2011)

Progesterone resistant ionic currents in granulosa cells. Data were generated by whole-cell patch-clamp performed in freshly isolated bovine granulosa cells. (a) Example time-series plot showing the effect of 10 μM prog on current evoked by 100 μM PregS. 100 μM lanthanum (La3+) was applied at the end as a quality control for the whole-cell recording. (b) For the experiment of (a), I–Vs in the presence of 100 μM PregS, with 10 μM prog (+10 prog), or 100 μM La3+. (c) As for (a), but mean currents normalised to pre-prog amplitudes (n = 4). (d) Example time-series plot showing the effect of 10 μM prog on current evoked by 10 μM PregS. (e) For the experiment of (d), I–Vs in the presence of 10 μM PregS, or with 10 μM prog (+10 prog). (f) As for (d), but mean currents normalised to pre-prog amplitudes (n = 5).
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3275754&req=5

fig0055: Progesterone resistant ionic currents in granulosa cells. Data were generated by whole-cell patch-clamp performed in freshly isolated bovine granulosa cells. (a) Example time-series plot showing the effect of 10 μM prog on current evoked by 100 μM PregS. 100 μM lanthanum (La3+) was applied at the end as a quality control for the whole-cell recording. (b) For the experiment of (a), I–Vs in the presence of 100 μM PregS, with 10 μM prog (+10 prog), or 100 μM La3+. (c) As for (a), but mean currents normalised to pre-prog amplitudes (n = 4). (d) Example time-series plot showing the effect of 10 μM prog on current evoked by 10 μM PregS. (e) For the experiment of (d), I–Vs in the presence of 10 μM PregS, or with 10 μM prog (+10 prog). (f) As for (d), but mean currents normalised to pre-prog amplitudes (n = 5).
Mentions: We speculated that progesterone regulation of TRPM3 might also be relevant to the female reproductive system where progesterone has potent biological effects. A previous report suggested TRPM3 expression in human ovaries [9]. There were no reports of functional TRPM3 channels in this context and so we investigated if functional channels exist by making whole-cell patch-clamp recordings from granulosa cells freshly isolated from bovine ovarian follicles [14]. In K+-current recording solutions, A-type K+-current was observed (Supplementary Fig. VI), as expected for this cell type [18]. In TRPM3 recording solutions, pregnenolone sulphate evoked large ionic currents but only after delays of several minutes (Fig. 11a, d), which is not expected for TRPM3 (cf.Fig. 3a). The I–Vs of the evoked currents were almost linear (Fig. 11b, e), which is not standard for TRPM3 (cf.Fig. 3b), although has been observed in some recordings [19]. Progesterone did not inhibit the currents evoked by pregnenolone sulphate (Fig. 11a–f). The data suggest that granulosa cells contain ionic currents that are stimulated by pregnenolone sulphate but that these currents may not be mediated by TRPM3 and are not inhibited by progesterone.

Bottom Line: Progesterone metabolites and 17β-oestradiol were also inhibitory but the effects were relatively small.Corticosteroids lacked effect.Relevance of TRPM3 or the progesterone effect to ovarian cells, which have been suggested to express TRPM3, was not identified.

View Article: PubMed Central - PubMed

Affiliation: Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK.

Show MeSH
Related in: MedlinePlus