Intended use

The intended use of these reagents is for the determination of vasoactive intestinal polypeptide (VIP) in human plasma.

For professional use within a laboratory.

This product is also available as research use only. Product code: RB 311 RUO

For complete product description, claims and use, please refer to the Instructions For Use. Contact your local representative for availability in your country.

Background

Vasoactive intestinal peptide (VIP) is a linear polypeptide containing 28 amino acid residues. The molecular weight is 3381. VIP is structurally related to secretin and to other members of the secretin family. The carboxyterminal amino acid of VIP (Asn) is amidated.

Immunocytochemical studies have shown that VIP is present in neurons throughout the gastrointestinal tract, the centrol and peripheral nervous systems, the salivary glands and the pancreas.

VIP stimulates water and bicarbonate secretion by the pancreas. VIP possesses the capacity to relax smooth muscle. Administration of VIP produces vasodilation and pulmonary broncho-

dilation and relaxes the lower eosophagaeal sphincter and smooth muscle of the fundus of the stomach.

VIP is believed to play crucial roles in the regulation of intestinal motility and intestinal epithelial ion and water transport.

Increased plasma immunoreactive VIP concentrations have been reported in patients with the WDHA syndrome (water, diarrhoea, hypokalemia and achlor hydria). Increased plasma levels of VIP have also been reported in patients with cirrhosis.

Technical information

VIP is analysed by the competitive radioimmunoassay using antibodies to a VIP-albumin conjugate. VIP in standards and samples compete with ¹²⁵I-labelled VIP in binding to the antibodies. ¹²⁵I-VIP binds in a reverse proportion to the concentration of VIP in standards and samples. In order to increase the sensitivity of the assay a sequential incubation is performed. Antibody-bound ¹²⁵I-VIP is separated from the unbound fraction using the double antibody polyethylene glycol precipitation technique. The radioactivity of the precipitates is measured. The antiserum used in this kit is directed to the C-terminal part of the VIP molecule.

Kit components and storage of reagents

The reagents provided in each kit are sufficient for 100 tubes.

Composition of the reagent kit

1. Anti-VIP (Reagent A)

Rabbit antiserum raised against highly purified porcine VIP conjugated to bovine serum albumin. Lyophilized in 2.0 mL 0.5 M phosphate buffer, pH 7.4, 4.0% human serum albumin, 0.5% sodium azide and 5000 KIU Trasylol^a per mL. For 100 tubes. Reconstitution in 22 mL distilled water. Colour: Yellow.

2. ¹²⁵I-VIP (Reagent B)

Contains 1.5 μCi or 56 KBq. Produced by iodination of synthetic, human VIP. HPLC-purified, monoiodinated. Specific activity: 1700-2100 μCi/nmol (62-77 Mbq/nmol).

Lyophilized in 1.25 mL 0.5 M phosphate buffer, pH 7.4, 4.0% human serum albumin,

0.5% sodium azide. Contains 0.12 mL normal rabbit serum and 6500 KIU Trasylol^a. Reconstitution in 12.5 mL distilled water. Colour: Blue.

3. Double antibody-PEG (Reagent C)

50 mL diluted goat anti-rabbit-Ig antiserum in 0.05 M phosphate buffer, pH 7.4, 0.4%

human serum albumin and 0.05% NaN₃. Contains 5.0% (w/v) polyethylene glycol 6000.

Colour: Red.

4. Standard diluent (Reagent D)

10.0 mL lyophilized human plasma for dilution of the VIP standards. Contains 500 KIU Trasylol^a per mL and 0.05% sodium azide. Reconstitution in 10.0 mL distilled water.

5. VIP standard (Reagent E)

5.00 mL, 120 pmol/L, synthetic human VIP. Lyophilized in human plasma. Contains 500 KIU Trasylol^? per mL and 0.05% sodium azide. Reconstitution in 5.00 mL distilled water.

6. Assay buffer (Reagent F)

5.0 mL buffer for use instead of antiserum in non-specific binding controls. 0.05 M phosphate buffer, pH 7.4, 0.4% human serum albumin, 0.5% sodium azide and 500 KIU Trasylol^ò per mL.

7. Controls (Reagent G-H)

Lyophilized plasma controls with low (normal) and high concentration of VIP. 2.00 mL of each control after reconstitution. The VIP concentrations are given on the labels of the vials.

Contains 0.05% sodium azide.

Reagent preparation and storage

Store all reagents at 2-8° C before reconstitution and use. The water used for reconstitution of lyophilized reagents should be destilled in an all-glass apparatus or be of corresponding purity. Dissolve the contents in a vial by gentle inversion and avoid foaming. The stability of the reagents is found on the label of the vials. For lyophilized reagents the expiry date is valid for the unreconstituted reagents. Reconstituted reagents are stable for 10 weeks stored correctly.