Molecular and electrical remodeling of L- and T-type Ca(2+) channels in rat right atrium with monocrotaline-induced pulmonary hypertension.
BACKGROUND
Atrial arrhythmia is often encountered in chronic pulmonary disease with pulmonary hypertension (PH), but few studies have investigated the electrical remodeling of atrial Ca(2+) channels under PH.


RESULTS
Wistar rats were injected with monocrotaline (MCT), resulting in PH with right atrial and ventricular hypertrophy. The L-type Ca(2+) channel current density was significantly decreased in right atrial cells of MCT-treated rats, accompanied by a significant reduction in mRNA expression of the CaV1.2 (alpha(1C)) subunit and accessory beta(2) subunit. Conversely, the low voltage-activated Ca(2+) current was more marked in the right atrial cells of MCT-treated rats than in those of control rats. The current-voltage relationship and the time course of inactivation closely resembled those of T-type Ca(2+) channels, although the current was only slightly inhibited by 10-100 micromol/L Ni(2+). No significant differences were observed in the mRNA expression levels of CaV3.1 (alpha(1G)) and CaV3.2 (alpha(1H)) or the protein level of the CaV3.1 subunit. In left atrial cells, the electrophysiological molecular properties of Ca(2+) channels were unaffected by MCT treatment.


CONCLUSIONS
PH causes right atrial hypertrophy, associated with alteration of the electrophysiological molecular properties of Ca(2+) channels.
Koyama
Takashi
T
Department of Cardiology, Akita University School of Medicine, Akita, Japan.
Ono
Kyoichi
K
Watanabe
Hiroyuki
H
Ohba
Takayoshi
T
Murakami
Manabu
M
Iino
Kenji
K
Ito
Hiroshi
H
D000818:Animals; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D022062:Electrophysiologic Techniques, Cardiac; D006325:Heart Atria / Q000378:metabolism* / Q000473:pathology; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D006984:Hypertrophy / Q000378:metabolism / Q000473:pathology; D017380:Hypertrophy, Right Ventricular / Q000378:metabolism / Q000473:pathology; D016686:Monocrotaline; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D012333:RNA, Messenger; D016686:Monocrotaline