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- Hou, Mingyan, et al.
(författare)
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Increase in cardiac P2X1-and P2Y2-receptor mRNA levels in congestive heart failure
- 1999
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Ingår i: Life Sciences. - 1879-0631. ; 65:11, s. 1195-1206
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Tidskriftsartikel (refereegranskat)abstract
- We wanted to study the expression of P2-receptors at the mRNA-level in the heart and if it is affected by congestive heart failure (CHF). To quantify the P2 receptor mRNA-expression we used a competitive RT-PCR protocol which is based on an internal RNA standard. The P2 receptor mRNA-expression was quantified in hearts from CHF rats and compared to sham-operated rats. Furthermore, the presence of receptor mRNA was studied in the myocardium from patients with heart failure. In the sham operated rats the G-protein coupled P2Y-receptors were expressed at a higher level than the ligand gated ion-channel receptor (P2X1). Among the P2Y-receptors the P2Y6-receptor was most abundantly expressed (P2Y6 > P2Y1 > P2Y2 = P2Y4 > P2X1). A prominent change was seen for the P2X1- and P2Y2-receptor mRNA levels which were increased 2.7-fold and 4.7-fold respectively in the myocardium from the left ventricle of CHF-rats. In contrast, the P2Y1-, P2Y4- and P2Y6-receptor mRNA levels were not significantly altered in CHF rats. In human myocard the P2X1-, P2Y1-, P2Y2-, P2Y6- and P2Y11-receptors were detected by RT-PCR in both right and left atria and ventricles, while the P2Y4-receptor band was weak or absent. In conclusion, most of the studied P2-receptors were expressed in both rat and human hearts. Furthermore, the P2X1- and P2Y2-receptor mRNA were upregulated in CHF, suggesting a pathophysiological role for these receptors in the development of heart failure.
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| 2. |
- Malmsjö, Malin, et al.
(författare)
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Congestive heart failure induces downregulation of P2X1-receptors in resistance arteries
- 1999
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Ingår i: Cardiovascular Research. - 1755-3245. ; 43:1, s. 219-227
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Congestive heart failure (CHF) is accompanied by enhanced peripheral sympathetic nerve activity, increased vascular resistance and impaired peripheral blood flow. Besides noradrenaline and neuropeptide Y, the sympathetic nervous system also releases ATP, which has contractile effects mediated by different subtypes of P2-receptors on the vascular smooth muscle cells. The present study was designed to examine postsynaptic changes of the contractile responses to ATP and other extracellular nucleotides in CHF. METHODS: CHF was induced by left coronary artery ligation resulting in a reproducible myocardial infarction in Sprague-Dawley rats. Contractile responses were examined in cylindrical segments of aorta and the mesenteric artery after endothelium removal. To determine if an altered response was regulated on the transcriptional level, competitive reverse transcription polymerase chain reaction (RT-PCR) was used to estimate the amount of P2X1-receptor mRNA. RESULTS: ATP, which is both a P2X1- and a P2Y-receptor agonist, induced a weaker contraction in the mesenteric artery from CHF as compared to sham operated rats. A decrease in both potency and maximum contraction was shown for the selective P2X1-receptor agonist, alpha beta-MeATP, in the mesenteric artery (pEC50 = 6.04 vs. 5.76, Cmax = 57% vs. 33%, sham vs. CHF operated rats), but not in the aorta. Competitive RT-PCR also revealed decreased P2X1-receptor mRNA levels in CHF operated rats in the mesenteric artery (9106 x 10(3) vs. 714 x 10(3) molecules/microgram, sham vs. CHF operated rats), while it remained unaltered in the aorta. To study the P2Y-receptor induced contractile effects, the P2X1-receptors were first desensitised with alpha beta-MeATP (10(-5) M for 8 min). After P2X1-receptors desensitisation, UTP and UDP induced strong contractions in both the mesenteric artery and in the aorta, while ATP and ADP were much less effective. These contractions were not altered by CHF, indicating that vascular contraction mediated by P2Y-receptors are unaffected by CHF. CONCLUSION: CHF induces downregulation of P2X1-receptor stimulated contraction in the mesenteric artery depending on decreased mRNA synthesis for the receptor, while the P2Y-receptor activity remains unchanged. Downregulation of P2X1-receptors appears to be specific for peripheral resistance arteries. This may represent a compensatory response to enhanced peripheral sympathetic nerve activity and increased vascular resistance in CHF.
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