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Maternal Diabetes (MD) Increases Large Conductance Ca2+‐activated K+ (BK) Currents Which Alter Action Potential (AP) Properties But Do Not Affect Excitability of Parasympathetic Cardiac Motoneurons (PCMNs) In The Nucleus Ambiguus (NA) of Neonatal Mice
Author(s) -
Lin Min,
Chen QingHui,
Li Lihua,
Wurster Robert D.,
Cheng Zixi Jack
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.810.4
Subject(s) - afterhyperpolarization , repolarization , chemistry , endocrinology , medicine , bk channel , iberiotoxin , biophysics , conductance , potassium channel , electrophysiology , neuroscience , physics , biology , condensed matter physics
In an accompanying abstract (Lin et al. EB 2010), we have demonstrated that MD increases small conductance Ca 2+ ‐activated K + (SK) currents which are associated with MD‐induced alteration of AP properties and attenuated excitability of PCMNs. Presently, we test the hypothesis that MD also alters BK currents. Neonatal mice from OVE26 diabetic (Type 1) mothers (NMDM) and normal FVB mothers (control) were used. XRITC was injected into the pericardial sac at P7–9 to label PCMNs. Two days later, XRITC‐labeled PCMNs in slices were identified. Whole‐cell (current and voltage) clamps were used to measure spike frequency, repolarization (half‐width), afterhyperpolarization (AHP), outward currents, and afterhyperpolarization currents (I AHP ). Compared to control, we found (p<0.05) that in NMDM that 1) Ca 2+ ‐sensitive transient outward currents and I AHP increased; 2) application of Ca 2+ ‐free solution increased half‐width and decreased AHP amplitude; 3) BK channel blockers ChTX or paxilline‐sensitive transient outward currents and I AHP increased; 4) blockade of BK channels with ChTX or paxilline increased AP half‐width and decreased AHP amplitude at 10 ms, but not at 50 ms; 5) application of ChTX or paxilline does not affect spike firing frequency in response to current injections in both control and NMDM. In contrast to SK channels, we suggest that MD increases BK currents which contribute to altered AP properties, but do not directly affect the attenuated excitability of PCMNs in NMDM. NIH R01 HL79636.