Limits...
Large conductance Ca²⁺-activated K⁺ (BK) channels promote secretagogue-induced transition from spiking to bursting in murine anterior pituitary corticotrophs.

Duncan PJ, Şengül S, Tabak J, Ruth P, Bertram R, Shipston MJ - J. Physiol. (Lond.) (2015)

Bottom Line: Anterior pituitary corticotroph cells are a central component of the hypothalamic-pituitary-adrenal (HPA) axis essential for the neuroendocrine response to stress.We reveal that BK channels do not play a significant role in the generation of spontaneous activity but are critical for the transition to bursting in response to CRH.In contrast, AVP promotes an increase in single spike frequency, a mechanism independent of BK channels but dependent on background non-selective conductances.

View Article: PubMed Central - PubMed

Affiliation: Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, EH8 9XD, UK.

No MeSH data available.


Related in: MedlinePlus

Genetic deletion of BK channels reduces bursting activityA, representative traces of corticotrophs isolated from BK−/− mice which also show a reduction in bursting following CRH/AVP stimulation (B). BK−/− cells show a higher event frequency following CRH/AVP compared to wild-type cells (C) but show a decrease in event duration (D). Data are means ± SEM (n > 6 per group). *P <0.05, **P <0.01, ANOVA compared to respective base values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4358680&req=5

fig08: Genetic deletion of BK channels reduces bursting activityA, representative traces of corticotrophs isolated from BK−/− mice which also show a reduction in bursting following CRH/AVP stimulation (B). BK−/− cells show a higher event frequency following CRH/AVP compared to wild-type cells (C) but show a decrease in event duration (D). Data are means ± SEM (n > 6 per group). *P <0.05, **P <0.01, ANOVA compared to respective base values.

Mentions: Current-clamp recordings revealed 4/6 BK−/− cells displayed spontaneous activity with 6/6 showing an increase in activity following CRH/AVP stimulation (Fig.8A and B). In comparison to paxilline-treated cells, corticotrophs isolated from BK−/− mice showed no difference in basal membrane potential (−53.7 ± 2.3 mV), frequency (0.40 ± 0.19 Hz), mean event duration (153 ± 106 ms) or burstiness factor (0.15 ± 0.11) compared to wild-type cells (n = 6). CRH/AVP exposure resulted in a significant (P = 0.00074) depolarisation to −45.1 ± 2.4 mV which was not significantly different to wild-type. CRH/AVP was able to induce a significant (P = 0.046) increase in firing frequency to 2.30 ± 0.79 Hz (Fig.8C). Interestingly, peak firing frequency was significantly (P = 0.040) elevated compared with controls (0.86 ± 0.18 Hz) representing a 2.7-fold increase in CRH/AVP-evoked activity. Following CRH/AVP stimulation, bursting activity was observed in 3/6 cells. Basal mean event duration was 153 ± 106 ms which did not significantly increase (305 ± 127 ms) following CRH/AVP (Fig.8D).


Large conductance Ca²⁺-activated K⁺ (BK) channels promote secretagogue-induced transition from spiking to bursting in murine anterior pituitary corticotrophs.

Duncan PJ, Şengül S, Tabak J, Ruth P, Bertram R, Shipston MJ - J. Physiol. (Lond.) (2015)

Genetic deletion of BK channels reduces bursting activityA, representative traces of corticotrophs isolated from BK−/− mice which also show a reduction in bursting following CRH/AVP stimulation (B). BK−/− cells show a higher event frequency following CRH/AVP compared to wild-type cells (C) but show a decrease in event duration (D). Data are means ± SEM (n > 6 per group). *P <0.05, **P <0.01, ANOVA compared to respective base values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358680&req=5

fig08: Genetic deletion of BK channels reduces bursting activityA, representative traces of corticotrophs isolated from BK−/− mice which also show a reduction in bursting following CRH/AVP stimulation (B). BK−/− cells show a higher event frequency following CRH/AVP compared to wild-type cells (C) but show a decrease in event duration (D). Data are means ± SEM (n > 6 per group). *P <0.05, **P <0.01, ANOVA compared to respective base values.
Mentions: Current-clamp recordings revealed 4/6 BK−/− cells displayed spontaneous activity with 6/6 showing an increase in activity following CRH/AVP stimulation (Fig.8A and B). In comparison to paxilline-treated cells, corticotrophs isolated from BK−/− mice showed no difference in basal membrane potential (−53.7 ± 2.3 mV), frequency (0.40 ± 0.19 Hz), mean event duration (153 ± 106 ms) or burstiness factor (0.15 ± 0.11) compared to wild-type cells (n = 6). CRH/AVP exposure resulted in a significant (P = 0.00074) depolarisation to −45.1 ± 2.4 mV which was not significantly different to wild-type. CRH/AVP was able to induce a significant (P = 0.046) increase in firing frequency to 2.30 ± 0.79 Hz (Fig.8C). Interestingly, peak firing frequency was significantly (P = 0.040) elevated compared with controls (0.86 ± 0.18 Hz) representing a 2.7-fold increase in CRH/AVP-evoked activity. Following CRH/AVP stimulation, bursting activity was observed in 3/6 cells. Basal mean event duration was 153 ± 106 ms which did not significantly increase (305 ± 127 ms) following CRH/AVP (Fig.8D).

Bottom Line: Anterior pituitary corticotroph cells are a central component of the hypothalamic-pituitary-adrenal (HPA) axis essential for the neuroendocrine response to stress.We reveal that BK channels do not play a significant role in the generation of spontaneous activity but are critical for the transition to bursting in response to CRH.In contrast, AVP promotes an increase in single spike frequency, a mechanism independent of BK channels but dependent on background non-selective conductances.

View Article: PubMed Central - PubMed

Affiliation: Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, EH8 9XD, UK.

No MeSH data available.


Related in: MedlinePlus