intestinal vasoactive peptide

Vasoactiveintestinal peptide (VIP) consists of 28 amino acids, mainly released by intestinal neurons, and is also abundant in the central nervous system. It is an important brain-gut peptide. There are also many VIP nerve fibers in the pancreas. Fat meal and vagus nerve stimulation can cause the release of VIP. In addition, intestinal ischemia can also stimulate its release. It has a wide range of biological activities, such as dilating heart, brain, hepatic blood vessels, regulating cerebral blood flow, reducing pulmonary artery pressure, lowering blood pressure, relaxing bronchial smooth muscle, regulating central body temperature, sleep, and stimulating prolactin release. The main role of the digestive system is to relax the intestinal smooth muscle and relax the lower esophageal sphincter, Oddi sphincter, intestinal smooth muscle, and anal internal sphincter. Basic Information Specialist classification: growth and development examination classification: blood examination Applicable gender: whether men and women apply fasting: not fasting Tips: VIP can stimulate the secretion of bile acid-independent bile, promote the decomposition of glycogen, and increase blood sugar. Normal value The RIA method is 20 to 53 ng/L (20 to 53 pg/ml). Clinical significance Increase WDHA syndrome (hyperdiarrhea hypokalemia with islet cell adenoma syndrome), short bowel syndrome, uremia, insulinoma and so on. High results may be diseases: uremia considerations In addition, VIP can stimulate the secretion of bile acid-independent bile, promote the decomposition of glycogen, and increase blood sugar. Inspection process The method is divided into three steps, namely antigen-antibody reaction, B and F separation, and radioactivity determination. (1) Reaction of antigen with antibody: The specimen (non-labeled antigen), labeled antigen and antiserum are sequentially dosed into a small test tube, and allowed to stand at room temperature (15 to 30 ° C) for 24 hours to fully compete for binding. (2) Separation of B and F: There are various separation techniques, and the precipitation method is commonly used. 1 second antibody precipitation method: also known as diabody method, after the test antigen specifically reacts with the first antibody, the corresponding second antibody is added, so that the formed antigen-first antibody-second antibody complex is co-precipitated. The labeled antigen B is separated from the free antigen F by centrifugation. This method is a specific precipitation, complete separation, low non-specific binding. However, the amount of the second antibody is large and the cost is high. In addition, the serum concentration and the presence or absence of anticoagulants can affect the results to some extent. 2 Polyethylene glycol (PEG) precipitation method: the protein is in an isoelectric point state, and the hydration layer is destroyed to cause protein precipitation. The advantage of this method is that PEG is convenient to prepare, inexpensive, and rapid to separate. The disadvantage is that there are many non-specific precipitates and the separation is incomplete. 3Second antibody-polyethylene glycol precipitation method: This method not only has the advantage of rapid precipitation of PEG method, but also maintains the effect of specific precipitation of second antibody, reduces the amount of second antibody, and reduces the concentration of PEG, so that non-specific precipitation Reduced material. 4 Activated carbon adsorption method: the free part of small molecules is adsorbed by the surface activity of activated carbon. For example, a layer of dextran is coated on the surface of the activated carbon to make a mesh having a certain pore diameter on the surface, thereby allowing small molecules of free antigen or hapten to escape and being adsorbed, while the macromolecular complex is excluded. After the antigen and the antibody are reacted, the dextran-activated carbon is added and allowed to stand for 5 to 10 minutes, so that the free antigen is adsorbed on the activated carbon particles, and the particles are precipitated by centrifugation, and the supernatant contains the labeled antigen. (3) Determination of radioactivity: After separation of B and F, the radioactivity can be measured. There are two types of measuring instruments: a liquid scintillation counter (measuring beta rays) and a crystal scintillation counter (measuring gamma rays). The unit of counting is the number of electrical pulses output by the detector in units of cpm (number of pulses/min). A standard curve is required for each measurement, and the different concentrations of the standard antigen are plotted on the abscissa, and the corresponding radioactivity measured is plotted on the ordinate. The radioactivity may be optionally B or F, and the calculated values ​​B/B+F, B/F or B/B0 may also be used. Specimens should be determined in duplicate, the average value is taken, and the corresponding antigen concentration is detected on the standard curve. Not suitable for the crowd No taboos. Adverse reactions and risks An infection may occur.

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