Finland i bilder = : Suomi kuvissa = La Finlande pittoresque : fotografier och text = kuvat ja teksti = photographies et texte I. K. Inha.

Text in Swedish, Finnish, French, German, Russian and English languages.

Developmental changes in hyperpolarization-activated currents I-h and I-K(IR) in isolated rat intracardiac neurons

The hyperpolarization-activated nonselective cation current, I-h, was investigated in neonatal and adult rat intracardiac neurons. I-h was observed in all neurons studied and displayed slow time-dependent rectification. I-h was isolated by blockade with external Cs+ (2 mM) and was inhibited irreversibly by the bradycardic agent, ZD 7288. Current density of I-h was approximately twofold greater in neurons from neonatal (-4.1 pA/pF at -130 mV) as compared with adult (-2.3 pA/pF) rats; however, the reversal potential and activation parameters were unchanged. The reversal potential and amplitude of I-h was sensitive to changes in external Na+ and K+ concentrations. An inwardly rectifying K+ current, I-K(IR), was also present in intracardiac neurons from adult but not neonatal rats and was blocked by extracellular Ba2+. I-K(IR) was present in approximately one-third of the adult intracardiac neurons studied, with a current density of -0.6 pA/pF at -130 mV. I-K(IR) displayed rapid activation kinetics and no time-dependent rectification consistent with the rapidly activating, inward K+ rectifier described in other mammalian autonomic neurons. I-K(IR) was sensitive to changes in external K+, whereby raising the external K+ concentration from 3 to 15 mM shifted the reversal potential by approximately +36 mV. Substitution of external Na+ had no effect on the reversal potential or amplitude of I-K(IR). I-K(IR) density increases as a function of postnatal development in a population of rat intracardiac neurons, which together with a concomitant decrease in I-h may contribute to changes in the modulation of neuronal excitability in adult versus neonatal rat intracardiac ganglia.

Recensao de: I. K. Healy, Social Work Practices: Contemporary Perspectives on Change, London, Sage, 2000.

Revista Lusófona de Ciências Sociais

Èkspedicìi k" ust'âm" Eniseâ 1875 i 1876 godov": so stat'eû ad"ûnkt" professora zoologìi Upsal'skago universiteta G. Tèlâ o plavanìi ego po Eniseû v" 1876 godu i dvu'mâ kartami plavanìâ

Perevod s" sÌŒvedskago.

Charta öfver Wasa höfdingedöme utgifven af friherre S. G. Hermelin författad af C. P. Hällström philos. mag. och ausc. vid auscultant i K. Bergs Coll.

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