VIP (Vasoactive Intestinal Peptide)¶
Vasoactive Intestinal Peptide (VIP, CAS 37221-79-7) is a 28-amino acid neuropeptide with a molecular weight of approximately 3,325.8 Da, originally isolated from porcine duodenum. VIP shares ~68% sequence homology with PACAP (pituitary adenylate cyclase-activating polypeptide) and belongs to the secretin/glucagon/VIP superfamily of class B GPCR ligands. Widely distributed in the central and peripheral nervous system, VIP functions as a potent vasodilator, smooth muscle relaxant, immunomodulator, and neurotransmitter. It is a versatile research tool in neuroimmunology, circadian biology, and smooth muscle physiology.
Technical Specifications¶
| Property | Value |
|---|---|
| CAS Number | 37221-79-7 |
| Molecular Formula | C₁₄₇H₂₃₈N₄₄O₄₂S |
| Molecular Weight | ~3,325.8 Da |
| Purity | ≥98% (HPLC-verified) |
| Appearance | Lyophilized white powder |
| Solubility | Soluble in aqueous buffers; limited water solubility |
| Storage | -20°C (lyophilized), 2–8°C (reconstituted) |
Mechanism of Action¶
VIP binds with high affinity to two class B GPCRs: VPAC1 and VPAC2 (also binds PAC1 with lower affinity). Both VPAC receptors couple to Gαs, activating adenylyl cyclase and elevating intracellular cAMP, which mediates most of VIP's biological effects. In vascular and non-vascular smooth muscle, cAMP activates PKA, which phosphorylates and inhibits myosin light chain kinase (MLCK), leading to profound vasodilation and smooth muscle relaxation — VIP is one of the most potent endogenous vasodilators. In the gastrointestinal tract, VIPergic neurons of the enteric nervous system mediate descending relaxation of the peristaltic reflex and regulate ion and water secretion in intestinal epithelium via cAMP-dependent CFTR channel activation. In the immune system, VIP shifts the Th1/Th2 balance toward Th2 dominance by inhibiting pro-inflammatory cytokine production (TNF-α, IL-12) from activated macrophages and dendritic cells while promoting IL-10 secretion. In the suprachiasmatic nucleus (SCN), VIP is the critical coupling factor that synchronizes circadian pacemaker neurons, with VIP/VPAC2 signaling essential for maintaining coherent circadian rhythmicity.
Research Applications¶
- Primary: Smooth muscle physiology — vasodilation mechanisms, enteric nervous system neurotransmission
- Secondary: Circadian rhythm synchronization (SCN coupling), neuroimmune modulation (Th1/Th2 balance), gastrointestinal secretion and motility
- Model Systems: In vitro (VPAC1/VPAC2-transfected cell lines, vascular ring myography, intestinal organoids), in vivo (circadian rhythm monitoring, inflammatory bowel disease models, systemic vasodilation studies)
Quality Control & Analytical Methods¶
- HPLC: ≥98% purity verification at 214/220 nm (C18 reversed-phase column)
- Mass Spectrometry: ESI-MS for molecular weight confirmation (~3,325.8 Da)
- Peptide Content: Amino acid analysis (AAA) for net peptide content determination
- Endotoxin: <1 EU/mg (LAL assay)
- TFA Content: <1% (ion chromatography)
Stability & Storage¶
| Condition | Stability |
|---|---|
| -20°C (lyophilized) | 24 months |
| 4°C (lyophilized) | 6 months |
| 25°C (lyophilized) | 1 month |
| Reconstituted (4°C) | 7 days |
| Reconstituted (-20°C) | 30 days |
Key Research References¶
- Said & Mutt (1970) — Polypeptide with broad biological activity: isolation from small intestine. Science. PMID: 4315261
- Harmar et al. (2012) — Pharmacology and functions of receptors for vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Pharmacol Rev. PMID: 22457463
- Aton et al. (2005) — Vasoactive intestinal polypeptide mediates circadian rhythmicity and synchrony in mammalian clock neurons. Nat Neurosci. PMID: 15713845
Source & Purchase¶
For researchers requiring research-grade VIP with full analytical documentation including HPLC, LC-MS, and Certificate of Analysis, visit the HK Peptides product page for specifications, bulk pricing, and ordering.
Related Molecules¶
- Oxytocin — Neurohypophyseal hormone, smooth muscle contraction
- DSIP — Delta sleep-inducing peptide, sleep architecture
- Kisspeptin-10 — GnRH regulator, neuroendocrine signaling
- All Product Specifications
FAQ¶
Q: What purity level is standard for VIP? A: HK Peptides supplies VIP at ≥98% purity by HPLC with full COA documentation.
Q: How should VIP be stored for research use? A: Lyophilized VIP should be stored at -20°C. Reconstituted solutions at 4°C for short-term use (up to 7 days).