Isoprenaline stimulates gene transcription of the inhibitory G protein alpha-subunit Gi alpha-2 in rat heart.
In vitro transcription reactions were performed with isolated ventricular nuclei of adult rats to investigate whether increased mRNA levels of the inhibitory G protein alpha-subunit Gi alpha-2 after prolonged in vivo stimulation with the beta-adrenoceptor agonist isoprenaline are caused by increased transcription. Rats were treated by a 4-day subcutaneous infusion of isoprenaline (2.4 mg/kg per day) or 0.9% NaCl as control. To avoid the influence of developmental expression patterns, adult rats were chosen for all experiments. Signals for Gi alpha-2 and the stimulatory G protein alpha-subunit Gs alpha were specific and due to hybridization of nascent mRNA transcripts. In the isoprenaline group the transcriptional activity of Gi alpha-2 gene increased to 140% of the control value, whereas gene specific hybridization for Gs alpha remained unchanged. These results show that increased Gi alpha-2 mRNA levels after stimulation with isoprenaline are at least partially caused by enhanced transcription of Gi alpha-2 mRNA.
Müller
F U
FU
Abteilung Allgemeine Pharmakologie, Universitäts-Krankenhaus Eppendorf, Universität Hamburg, FRG.
Boheler
K R
KR
Eschenhagen
T
T
Schmitz
W
W
Scholz
H
H
D000818:Animals; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014158:Transcription, Genetic / Q000187:drug effects*
D019204:GTP-Binding Proteins; D007545:Isoproterenol