Premium
Maternal Diabetes Increases Small Conductance Ca2+‐activated K+ (SK) Currents Which Alters Action Potential Properties and Excitability of Cardiac Motoneurons in the Nucleus Ambiguus
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.625.13
Subject(s) - afterhyperpolarization , apamin , repolarization , medicine , endocrinology , chemistry , electrophysiology , cardiology , biophysics , potassium channel , biology
Maternal diabetes (MD) impairs baroreflex control of heart rate. PCMNs play a key role in the baroreflex. We examined the effects of MD on excitability, action potential (AP) properties and SK channels of PCMNs. 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) in NMDM that: 1) spike frequency decreased; 2) the half‐width and AHP peak amplitude increased; 3) the peak amplitude of outward transient currents and I AHP increased; 4) Cd 2+ (Ca 2+ channels blocker)‐sensitive transient outward currents and I AHP increased; 5) application of Cd 2+ increased AP half‐width and decreased AHP amplitude; 6) apamin‐sensitive transient outward currents and I AHP increased; 7) blockade of SK channels with apamin increased AP half‐width and decreased AHP amplitude; 8) apamin application increased the firing rate to current injections and largely abolished the difference of the firing rate between control and NMDM. We suggest that the augmented SK currents may contribute to altered AP properties and the attenuated excitability of PCMNs in NMDM. NIH R01 HL79636.