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Enrichment of G protein alpha-subunit mRNAS in the AV-conducting system of the mammalian heart.

Abstract：

:We investigated the expression pattern of the heterotrimeric G proteins Gs alpha, Gi alpha-2 and Go alpha in rat and guinea-pig heart by in situ hybridization. Cryosections were hybridized with single-stranded 35S-cRNA probes complementary to subtype-specific sequences of the respective mRNAs. Hybridization signals were visualized by exposition to X-ray films and dipping autoradiography. The rank order of abundance was Gi alpha-2 approximately Gs alpha > Go alpha. In general, G protein alpha-subunit mRNAs were evenly distributed in the heart including endo- and epicardium, large vessels and valves. Go alpha-mRNA levels were significantly higher in atria than in ventricles. In contrast to the rather uniform labeling of working myocardium, expression of all three G proteins was enriched in small intramural blood vessels and in subendocardial Purkinje fibers of septum and papillary muscles. A more marked enrichment of Gs alpha-, Gi alpha-2- and especially Go alpha-mRNA was seen in neuronal ganglionic cells in the atrial septum and posterior regions of the atrium. The main finding, however, was an enrichment of all three G protein mRNAs in the atrioventricular conductive tissue. The accumulation was strictly co-localized with acetylcholinesterase-positive regions identified as the atrioventricular node, the bundle of His and the right and left bundle branches and was seen similarly in rat and guinea-pig hearts. Quantitative in situ hybridization revealed Gs alpha-, Gi alpha-2- and Go alpha-mRNA levels in the bundle of His to be 206 +/- 0.13%. 191 +/- 0.15% and 165 +/- 0.06%, respectively, of that in the surrounding interventricular working myocardium. These findings indicate that heterotrimeric G proteins play an important role in modulation of electrical conductance in the heart.

journal_name

J Mol Cell Cardiol

journal_title

Journal of molecular and cellular cardiology

authors

Eschenhagen T,Laufs U,Schmitz W,Scholz H,Warnholtz A,Weil J,Schäfer HJ

doi

10.1016/s0022-2828(95)91659-8

subject

Has Abstract

pub_date

1995-10-01 00:00:00

pages

2249-63

issue

eissn

0022-2828

issn

1095-8584

pii

S0022-2828(95)91659-8

journal_volume

pub_type

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Enrichment of G protein alpha-subunit mRNAS in the AV-conducting system of the mammalian heart.