Frequency-dependent action potential prolongation in Aplysia pleural sensory neurones

Neuroscience ◽  
1985 ◽  
Vol 16 (2) ◽  
pp. 451-460 ◽  
Author(s):  
J.P. Edstrom ◽  
K.D. Lukowiak
Keyword(s):  
Action Potential ◽  
Frequency Dependent ◽  
Sensory Neurones ◽  
Action Potential Prolongation

Preceding Stimulus Frequency-Dependent Potentiation of the Postrest Shortening of the Action Potential Duration in Rabbits.

2000 ◽  
Vol 41 (4) ◽  
pp. 481-492
Author(s):  
Naohiko Takahashi ◽  
Morio Ito ◽  
Shuji Ishida ◽  
Takao Fujino ◽  
Mikiko Nakagawa ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Stimulus Frequency ◽  
Frequency Dependent ◽  
Preceding Stimulus

Effects of relaxin on rat atrial myocytes. II. Increased calcium influx derived from action potential prolongation

1997 ◽  
Vol 272 (4) ◽  
pp. H1798-H1803 ◽  
Author(s):  
E. S. Piedras-Renteria ◽  
O. D. Sherwood ◽  
P. M. Best
Keyword(s):  
Action Potential ◽  
Calcium Influx ◽  
Calcium Currents ◽  
Atrial Myocytes ◽  
Inotropic Effects ◽  
Whole Cell Patch Clamp ◽  
Rat Hearts ◽  
Action Potential Prolongation ◽  
Dose Dependent ◽  
Rat Atrial Cells

Relaxin produces positive inotropic and chronotropic effects in rat hearts. The effect of relaxin on the action potential duration (APD) of single quiescent rat atrial cells was investigated with a whole cell patch clamp. Relaxin induced a significant, dose-dependent prolongation of the APD. This effect was maximal at 200 ng/ml (nominal concentration of 33.6 nM), which caused, on average, a 57% increase in the time taken to reach 90% repolarization. The effect of relaxin was blocked by the protein kinase A inhibitor 5-24 amide, indicating that its effect is mediated by an adenosine 3',5'-cyclic monophosphate-dependent mechanism. The increased APD induced by relaxin caused an enhanced entrance of calcium, with the charge carried through voltage-activated calcium channels increased by approximately 25%. This increase was not due to a direct modulation of calcium currents (20); rather, it was a consequence of the longer period of cellular depolarization. Our findings that relaxin increased the APD and therefore increased the calcium influx in atrial myocytes could explain the positive inotropic effects induced by relaxin in atrial preparations.

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