Properties of synchronous spontaneous Ca2+ transients in the mural cells of rat rectal arterioles.
Pflugers Arch
; 469(9): 1189-1202, 2017 09.
Article
em En
| MEDLINE
| ID: mdl-28429070
ABSTRACT
Synchrony of spontaneous Ca2+ transients among venular mural cells (smooth muscle cells and pericytes) in visceral organs relies on the intercellular spread of L-type voltage-dependent Ca2+ channel (LVDCC)-dependent depolarisations. However, the mechanisms underlying the synchrony of spontaneous Ca2+ transients between arteriolar mural cells are less understood. The spontaneous intracellular Ca2+ dynamics of arteriolar mural cells in the rat rectal submucosa were visualised by Cal-520 Ca2+ imaging to analyse their synchrony. The mural cells in fine arterioles that had a rounded cell body with several extended processes developed spontaneous 'synchronous' Ca2+ transients arising from Ca2+ released from sarcoendoplasmic reticulum Ca2+ stores. Gap junction blockers (3 µM carbenoxolone, 10 µM 18ß-glycyrrhetinic acid), a Ca2+-activated Cl- channel (CaCC) blocker (100 µM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) or lowering extracellular Cl- concentration (from 134.4 to 12.4 mM) disrupted the synchrony of Ca2+ transients between arteriolar mural cells. Blockers of T-type voltage-dependent Ca2+ channels (TVDCCs, 1 µM mibefradil or ML218) or LVDCCs (1 µM nifedipine) reduced the Ca2+ transient frequency or their area under curve (AUC), respectively. However, neither TVDCC nor LVDCC blockers disrupted the synchrony of Ca2+ transients among arteriolar mural cells. This is in contrast with rectal venules in which nifedipine disrupted the synchrony of spontaneous Ca2+ transients. Thus, spontaneous transient depolarisations arising from the opening of CaCCs may effectively spread to neighbouring arteriolar mural cells via gap junctions to maintain the Ca2+ transient synchrony. Activation of TVDCCs appears to accelerate spontaneous Ca2+ transients, while LVDCCs predominantly contribute to the duration of Ca2+ transients.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Arteríolas
/
Reto
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Cálcio
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Pericitos
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Miócitos de Músculo Liso
Limite:
Animals
Idioma:
En
Revista:
Pflugers Arch
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Japão