GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Effects of ghrelin on the intracellular calcium concentration in rat aorta vascular smooth muscle cells.
Fang. Huan H; Hong. Zhen Z; Zhang. Jun J; Shen. Dai-Fei DF; Gao. Fen-Fei FF; Sugiyama. Kenji K; Namba. Hiroki H; Asakawa. Tetsuya T
Key Findings
- Vascular smooth muscle cells express the ghrelin receptor (GHS‑R1a).
- Ghrelin prevents the angiotensin II‑induced rise in intracellular calcium in these cells.
- The protective effect is reversed by a GHS‑R1a antagonist and an adenylate cyclase inhibitor, indicating reliance on the cAMP/PKA pathway.
- Ghrelin has no effect on calcium levels in resting cells or when calcium is raised by potassium chloride.
Practical Outcomes
- The study suggests ghrelin could act as a vasodilator by blocking angiotensin‑II‑driven calcium spikes, which might help lower blood pressure or improve vascular health. However, the work is done in isolated rat cells, so there’s no direct dosing guidance for humans. Biohackers should view this as mechanistic insight that may inform future research or experimental use of ghrelin‑based peptides, but it isn’t ready for practical protocols yet.
Summary
In a lab study on rat blood vessel cells, the hormone ghrelin was found to stop a chemical (angiotensin II) that normally raises calcium inside the cells, which is a step that leads to vessel tightening. This blocking effect needs the ghrelin receptor and a signaling pathway called cAMP/PKA, and it disappears if the receptor is blocked. Ghrelin didn't change calcium levels in resting cells or when the cells were stimulated by potassium.
Abstract
Ghrelin has been regarded as a cardioprotective factor with complicated mechanisms. Whether ghrelin is vasodilative or vasoconstrictive in nature is controversial, and the effects of ghrelin on intracellular calcium concentration are still unclear. To explore the mechanisms involved in the vasoactive regulation of ghrelin at the cellular level, we investigated the effects of ghrelin on calcium concentrations in rat aorta vascular smooth muscle cells (VSMCs). We obtained VSMCs via cell culture and stained the cells with Furo-2 AM. Western blotting was used to verify growth hormone secretagogue receptor (GHS-R1a) expression in VSMCs. The intracellular calcium variations affected by ghrelin and the interactions of ghrelin with angiotensin II (AngII), Sq22536, and potassium chloride (KCl) were observed using a calcium imaging and analysis system. Western blotting revealed good GHS-R1a expression in VSMCs. The most prominent finding in the present study was that ghrelin inhibited the AngII-induced increase in the calcium concentration. This inhibition was reversed by the adenylate cyclase inhibitor Sq22536 and the GHS-R1a antagonist (D-Lys(3))- GHRP-6. This finding revealed the potential vasodilative effects of ghrelin at the cellular level. We did not observe any effects of ghrelin on intracellular calcium concentrations in resting VSMCs or the increase of calcium concentration induced by KCl. Ghrelin inhibited the increase in the intracellular calcium concentration of rat aorta VSMCs induced by AngII, which may depend on the activation of the cAMP/PKA pathway.
Study Information
pubmed
2012
2012-10-22T00:00:00.000Z
10.1159/000343319
13
56