Comparative study of cardiac electrophysiological effects of atrial natriuretic peptide.
The effects of atrial natriuretic peptide (ANP) on action potential characteristics were studied in various (human, rabbit, guinea-pig) atrial and guinea-pig right ventricular papillary muscles. ANP (1-100 nM) did not modify the resting membrane potential nor the maximum rate of depolarization phase (Vmax). Up to 10 nM, ANP dose-dependently decreased the action potential amplitude both in guinea-pig atrial and ventricular muscles, but it did not affect this parameter in the other atrial preparations. ANP caused a dose-dependent, marked decrease of action potential duration (APD) in practically every cardiac preparation studied (exception of guinea-pig left atrium). The strongest effect on APD can be observed in human atrial and guinea-pig ventricular fibers. The K+ channel blocker 4-aminopyridine (1 mM) and the ATP-dependent K+ channel inhibitor glibenclamide (10 microM) prevented the effect of ANP on APD in both ventricular atrial preparations. ANP prevented the appearance of isoprenaline (0.5 microM) induced slow AP in K+ depolarized myocardium. The present data suggest that ANP may inhibit the slow inward Ca2+ channel activity and facilitate the K+ channel activity.
Department of Pharmacology, Semmelweis University of Medicine, Budapest, Hungary.
V
V
Kecskemeti
P
P
Pacher
C
C
Pankucsi
P
P
Nanasi
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D004232:Diuretics / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005905:Glyburide / Q000494:pharmacology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D010446:Peptide Fragments; D011817:Rabbits
D000959:Antihypertensive Agents; D004232:Diuretics; D010446:Peptide Fragments; C062525:atrial natriuretic factor prohormone (103-126); D009320:Atrial Natriuretic Factor; D015761:4-Aminopyridine; D005905:Glyburide