Abstract
Spontaneous contractions of the myosalpinx are critical for oocyte transport along the oviduct. Slow waves, the electrical events that underlie myosalpinx contractions, are generated by a specialized network of pacemaker cells called oviduct interstitial cells of Cajal (ICC-OVI). The ionic basis of oviduct pacemaker activity is unknown. Intracellular recordings and Ca 2+ imaging were performed to examine the role of extracellular and intracellular Ca 2+ sources in slow wave generation. RT-PCR was performed to determine the transcriptional expression of Ca 2+ channels. Molecular studies revealed most isoforms of L- and T-type calcium channels (Cav1.2,1.3,1.4,3.1,3.2,3.3) were expressed in myosalpinx. Reduction of extracellular Ca 2+ concentration ([Ca 2+]o) resulted in the abolition of slow waves and myosalpinx contractions without significantly affecting resting membrane potential (RMP). Spontaneous Ca 2+ waves spread through ICC-OVI cells at a similar frequency to slow waves and were inhibited by reduced [Ca 2+] o. Nifedipine depolarized RMP and inhibited slow waves; however, pacemaker activity returned when the membrane was repolarized with reduced extracellular K + concentration ([K +] o). Ni 2+ also depolarized RMP but failed to block slow waves. The importance of ryanodine and inositol 1,4,5 trisphosphate-sensitive stores were examined using ryanodine, tetracaine, caffeine, and 2-aminoethyl diphenylborinate. Results suggest that although both stores are involved in regulation of slow wave frequency, neither are exclusively essential. The sarco/endoplasmic reticulum Ca 2+-ATPase (SERCA) pump inhibitor cyclopiazonic acid inhibited pacemaker activity and Ca 2+ waves suggesting that a functional SERCA pump is necessary for pacemaker activity. In conclusion, results from this study suggest that slow wave generation in the oviduct is voltage dependent, occurs in a membrane potential window, and is dependent on extracellular calcium and functional SERCA pumps.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 301 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 2011 |
| Externally published | Yes |
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Keywords
- Interstitial cells of cajal
- Oocyte transport
- Smooth muscle
ASJC Scopus subject areas
- Cell Biology
- Physiology
Cite this
Electrical slow waves in the mouse oviduct are dependent on extracellular and intracellular calcium sources. / Dickson, Rose Ellen; Britton, Fiona C.; Baker, Salah A.; Hennig, Grant W.; Rollings, Christina M.; Sanders, Kenton M.; Ward, Sean M.
In: American Journal of Physiology - Cell Physiology, Vol. 301, No. 6, 12.2011.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Electrical slow waves in the mouse oviduct are dependent on extracellular and intracellular calcium sources
AU - Dickson, Rose Ellen
AU - Britton, Fiona C.
AU - Baker, Salah A.
AU - Hennig, Grant W.
AU - Rollings, Christina M.
AU - Sanders, Kenton M.
AU - Ward, Sean M.
PY - 2011/12
Y1 - 2011/12
N2 - Spontaneous contractions of the myosalpinx are critical for oocyte transport along the oviduct. Slow waves, the electrical events that underlie myosalpinx contractions, are generated by a specialized network of pacemaker cells called oviduct interstitial cells of Cajal (ICC-OVI). The ionic basis of oviduct pacemaker activity is unknown. Intracellular recordings and Ca 2+ imaging were performed to examine the role of extracellular and intracellular Ca 2+ sources in slow wave generation. RT-PCR was performed to determine the transcriptional expression of Ca 2+ channels. Molecular studies revealed most isoforms of L- and T-type calcium channels (Cav1.2,1.3,1.4,3.1,3.2,3.3) were expressed in myosalpinx. Reduction of extracellular Ca 2+ concentration ([Ca 2+]o) resulted in the abolition of slow waves and myosalpinx contractions without significantly affecting resting membrane potential (RMP). Spontaneous Ca 2+ waves spread through ICC-OVI cells at a similar frequency to slow waves and were inhibited by reduced [Ca 2+] o. Nifedipine depolarized RMP and inhibited slow waves; however, pacemaker activity returned when the membrane was repolarized with reduced extracellular K + concentration ([K +] o). Ni 2+ also depolarized RMP but failed to block slow waves. The importance of ryanodine and inositol 1,4,5 trisphosphate-sensitive stores were examined using ryanodine, tetracaine, caffeine, and 2-aminoethyl diphenylborinate. Results suggest that although both stores are involved in regulation of slow wave frequency, neither are exclusively essential. The sarco/endoplasmic reticulum Ca 2+-ATPase (SERCA) pump inhibitor cyclopiazonic acid inhibited pacemaker activity and Ca 2+ waves suggesting that a functional SERCA pump is necessary for pacemaker activity. In conclusion, results from this study suggest that slow wave generation in the oviduct is voltage dependent, occurs in a membrane potential window, and is dependent on extracellular calcium and functional SERCA pumps.
AB - Spontaneous contractions of the myosalpinx are critical for oocyte transport along the oviduct. Slow waves, the electrical events that underlie myosalpinx contractions, are generated by a specialized network of pacemaker cells called oviduct interstitial cells of Cajal (ICC-OVI). The ionic basis of oviduct pacemaker activity is unknown. Intracellular recordings and Ca 2+ imaging were performed to examine the role of extracellular and intracellular Ca 2+ sources in slow wave generation. RT-PCR was performed to determine the transcriptional expression of Ca 2+ channels. Molecular studies revealed most isoforms of L- and T-type calcium channels (Cav1.2,1.3,1.4,3.1,3.2,3.3) were expressed in myosalpinx. Reduction of extracellular Ca 2+ concentration ([Ca 2+]o) resulted in the abolition of slow waves and myosalpinx contractions without significantly affecting resting membrane potential (RMP). Spontaneous Ca 2+ waves spread through ICC-OVI cells at a similar frequency to slow waves and were inhibited by reduced [Ca 2+] o. Nifedipine depolarized RMP and inhibited slow waves; however, pacemaker activity returned when the membrane was repolarized with reduced extracellular K + concentration ([K +] o). Ni 2+ also depolarized RMP but failed to block slow waves. The importance of ryanodine and inositol 1,4,5 trisphosphate-sensitive stores were examined using ryanodine, tetracaine, caffeine, and 2-aminoethyl diphenylborinate. Results suggest that although both stores are involved in regulation of slow wave frequency, neither are exclusively essential. The sarco/endoplasmic reticulum Ca 2+-ATPase (SERCA) pump inhibitor cyclopiazonic acid inhibited pacemaker activity and Ca 2+ waves suggesting that a functional SERCA pump is necessary for pacemaker activity. In conclusion, results from this study suggest that slow wave generation in the oviduct is voltage dependent, occurs in a membrane potential window, and is dependent on extracellular calcium and functional SERCA pumps.
KW - Interstitial cells of cajal
KW - Oocyte transport
KW - Smooth muscle
UR - http://www.scopus.com/inward/record.url?scp=82455175851&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=82455175851&partnerID=8YFLogxK
U2 - 10.1152/ajpcell.00293.2011
DO - 10.1152/ajpcell.00293.2011
M3 - Article
C2 - 21881003
AN - SCOPUS:82455175851
VL - 301
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6143
IS - 6
ER -