Effects of atrionatriuretic factor on Ca2+current and Cai-independent transient outward K+current in human atrial cells

✍ Scribed by B. Grand; E. Deroubaix; J. -P. Couétil; E. Coraboeuf

• Publisher: Springer
• Year: 1992
• Tongue: English
• Weight: 604 KB
• Volume: 421
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370260

✦ Synopsis

The effect of l0 nM atrial natriuretic peptide (ANF) on macroscopic L-type calcium current,/Ca, and calcium-independent outward potassium current, Ilo, were studied in myocytes isolated from human atrial trabeculae using the whole-cell-recording patch-clamp technique. When cells were dialysed with pipette media containing 0.2 mM GTP, ANF reduced /'Ca by 37.81%+5.4% at +20mV and 11o by 21.72%+3.68% at + 60 mV in a reversible manner. When/Ca was increased by fl-adrenoreceptor stimulation (0.1 ~tM isoproterenol) or by the phosphodiesterase inhibitor isobutylmethylxanthine (10 gM) ANF reduced ICa by 24.99+3.4% and by 39.9___6.3% respectively. In cells dialysed with GTP-free pipette media, ANF increased /-Ca markedly (39.8% +7%) and reversibly, whereas it still depressed Ilo (18.92% ___2%). Addition of 0.2 mM GTP[yS] to the pipette solution in the absence of GTP increased/-ca, decreased ILo and suppressed the effect of ANF on both Ica and/lo. It is suggested that activation of the ANF receptor in human atrial cells reduces Ica via guanylate-cyclase-dependent cGMP production, increases/-Ca via Gs protein activation and decreases Ilo via Gi protein activation.