Voltage-gated currents in identified parasympathetic cardiac neurons in the nucleus ambiguus

Brain Research
M MihalevichD Mendelowitz

Abstract

Heart rate is normally dominated by the activity of the cardioinhibitory parasympathetic nervous system, while abnormally low levels of parasympathetic cardiac activity have been implicated in many cardiovascular diseases including hypertension, heart failure and sudden cardiac death. In this study we have examined the voltage-gated currents in parasympathetic cardiac neurons that were identified with a retrograde fluorescent tracer in visualized sections (250 microns) of nucleus ambiguus. Depolarization of parasympathetic cardiac neurons to potentials more positive than -50 mV evoked a rapidly activating and inactivating inward current which could be blocked by tetrodotoxin (TTX), although in some neurons up to 10 microM was required for complete block. The voltage-dependent inactivation properties of this Na current showed relatively broad inactivation characteristics, a characteristic of TTX-resistant Na channels. Depolarization also elicited biphasic outward currents, which were separated into a transient IA type K current using the specific channel antagonist 4-aminopyridine and a long-lasting delayed rectified K current. These voltage-gated Na and K currents define the action potential firing patterns of parasympathetic c...Continue Reading

Citations

Jul 23, 1998·Clinical and Experimental Pharmacology & Physiology·D Mendelowitz
Jun 8, 2001·News in Physiological Sciences : an International Journal of Physiology Produced Jointly by the International Union of Physiological Sciences and the American Physiological Society·David Mendelowitz
Jan 10, 2002·American Journal of Therapeutics·Jack L SegalDavid C Bunten
Oct 30, 2012·Experimental Physiology·G Cristina BrailoiuEugen Brailoiu
Dec 7, 2002·Toxicon : Official Journal of the International Society on Toxinology·Evanguedes KalapothakisAlvair Pinto de Almeida

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