Effects of urocortin on T-type calcium currents in mouse spermatogenic cells.
Urocortin (UCN), a newly isolated peptide, has been found to play an important role mainly in female reproductive system. In order to investigate the effect of UCN on T-type calcium currents (I(Ca,T)), exploring the mechanisms of UCN's role in male reproductive system, especially in acrosome reaction, we directly measured the I(Ca,T) in mouse spermatogenic cells exposed to UCN using standard whole-cell patch-clamp recording technique. Our results showed that UCN reversibly inhibited the T-type Ca(2+) currents in the cells in a concentration-dependent manner. The current density was inhibited by about 19% after exposure of the cells to UCN (0.1 microM) for 5 min, from the control value of 6.75+/-1.17 to 5.26+/-0.82pA/pF. UCN up-shifted the current-voltage (I-V) curve. Frequency-dependence of UCN's effects on I(Ca,T) was also observed. Moreover, UCN at 0.1 microM did not markedly affect the activation of I(Ca,T) but shifted the inactivation curve of I(Ca,T) to the left. The inhibitory effect of UCN on the T-type Ca(2+) current was not affected by Astressin, the CRF receptor blocker. Since T-type calcium channels are a key component in acrosome reaction, our data suggest that UCN might be a significant factor in male reproductive action and a potential contraceptive agent.
Tao
Jin
J
Laboratory of Reproductive Medicine, Department of Pharmacology, Nanjing Medical University, Nanjing 210029, PR China.
Wu
Yuqing
Y
Chen
Jie
J
Zhu
Hui
H
Li
Shengnan
S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000187:drug effects / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015640:Ion Channel Gating / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D013091:Spermatogenesis / Q000187:drug effects / Q000502:physiology; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D054832:Urocortins
D020747:Calcium Channels, T-Type; D054832:Urocortins; D003346:Corticotropin-Releasing Hormone; D002118:Calcium