what is glucagon, what does glucagon do is a peptide hormone, produced by alpha cells of the pancreas. It raises the concentration of glucose and fatty acids in the bloodstream and is considered to be the main catabolic hormone of the body. It is also used as a medication to treat a number of health conditions. Its effect is opposite to that of insulin, which lowers extracellular glucose. It is produced from proglucagon, encoded by the GCG gene.
The pancreas releases buy glucagon when the amount of glucose in the bloodstream is too low. Glucagon causes the liver to engage in glycogenolysis: converting stored glycogen into glucose, which is released into the bloodstream. High blood-glucose levels, on the other hand, stimulate the release of insulin. Insulin allows glucose to be taken up and used by insulin-dependent tissues. Thus, glucagon and insulin are part of a feedback system that keeps blood glucose levels stable. Glucagon increases energy expenditure and is elevated under conditions of stress. Glucagon belongs to the secretin family of hormones.
Clinical implications
Hyperglucagonemia is usually caused by the excessive production of glucagon by a tumor of the pancreatic α cells (glucagonoma). Hyperglucagonemia can also occur in diverse conditions such as acute pancreatitis, severe stress, acromegaly, Cushing’s syndrome, hepatocirrhosis, chronic hepatitis, chronic renal insufficiency, diabetic ketoacidosis, prolonged starvation, hypercorticism, septicemia, and familial hyperglucagonemia. Manifestations of hyperglucagonemia include dermatitis, diabetes, diarrhea, weight loss, abdominal pain, anemia, and thromboembolic disease. Hypoglucagonemia is rare, and can occur in conditions such as chronic pancreatitis, anterior pituitary failure, Addison’s disease, and glucagon deficiency.
Pharmacological effects
The main role of glucogon is to promote the decomposition of glycogen and the production of glucose to elevate blood sugar; secondly, it also can promote lipolysis by leaving cyclic AMP (cAMP) levels increased via adenylate cyclase, thereby activating protein kinase and tissue lipase; in addition, through the activation of cardiac adenylate cyclase system, and promoting myocardial phosphorylase activity, it can increase the accumulation of calcium in the myocardium, thereby enhance myocardial contractility, increase cardiac output and blood pressure; It can promote insulin, somatostatin, thyroxine and calcitonin secretion; moreover, promote sympathetic and pheochromocyte catecholamines release.
Through glucagon and insulin, somatostatin co-regulation, blood sugar maintained at the normal range. The secretion of glucagon is inversely proportional to the concentration of glucose in the blood, and the secretion of glucagon is also affected by the contents of amino acids, plasma free fatty acids, α-adrenergic receptor stimulator (norepinephrine), growth hormone releasing inhibiting hormone and other factors.
Physiological
Glucagon is a single chain polypeptide hormone synthesized and secreted by islet α2 cells and it is a physiological antagonist of insulin. The impact on metabolism is similar to epinephrine. It has the following effects:
1. Blood glucose elevating effects: it can activate the phosphorylase in the liver, promote hepatic glycogen decomposition and gluconeogenesis, thus increasing blood sugar.
2. Positive inotropic action: it can increase intracellular cAMP levels, enhance myocardial contractility, increase cardiac output and stroke volume. Its positive inotropic effect can still manifest when applied with sufficient cardiac glycoside, and it will not be blocked by propranolol. Although it can increase heart rate and blood pressure, but will not cause arrhythmia. The mechanism is as follows: ①the activation of adenylate cyclase turned adenosine triphosphate into cyclization of adenosine monophosphate, making the myocardial contractility increased;
② promoting liver glycogen breakdown and increasing blood glucose levels;
③ promoting insulin release, improving the use of myocardial glucose and promoting myocardial anaerobic glycolysis, thereby improving myocardial energy metabolism. When combined with digitalis cardiac glycosides, It can increase the efficacy.
3. The role on the kidney: expanding renal blood vessels, improving renal blood flow, and promoting the excretion of sodium, potassium and calcium.
4. The role on the digestive system: it can cause the smooth muscle relaxation of stomach and duodenum, small intestine and colon and inhibit stomach, small intestine and colon peristalsis, increase the secretion of bile and intestinal fluid.
5. The role on the secretion system: exciting adrenal medulla, promoting the release of catecholamines. It can also promote insulin, thyroid hormone, calcitonin and growth hormone secretion.glucagon like peptide
Indications
Oral administration of this product is invalid, injection treatment is frequently applied. The action time in vivo is short; it will work after 5 minutes of intravenous injection. Blood glucose can be increased by 50% in 30 minutes. It is sustainable about 1 hour. It mainly inactivated in the liver, kidney and plasma. Plasma half-life time is 3 to 6 minutes. In clinical practice, it is used for insulin-dependent diabetes patients with severe hypoglycemic coma and the disability to eat, but also for the determination of pancreatic function, diagnosis of pancreatic tumor and pheochromocytoma. It is mainly used for acute heart failure, digitalis ineffective heart failure, heart failure with cardiogenic shock for circulatory system use. The efficacy of glucagon on chronic heart failure is poor. The main indications are as follows:
① acute low-emission syndrome.
② coronary heart disease and cardiomyopathy caused by acute heart failure or cardiogenic shock.
③ arrhythmia caused by the combined treatment of propranolol to digitalis poisoning.
Pharmacy
Usage and dosage 3~5mg for the first administration; intravenous injection of glucose solution. If there are no adverse reactions after 2~5min , intravenous infusion rate of 2.5~10mg/h is available. It will work after 1~3min of intravenous injection, 10min arrives at the peak, 30min effect disappears. It can be applied 24h continuously depending on the medical necessity.
Intramuscular, subcutaneous or intravenous: hypoglycemic coma, 0.5~1mg, if necessary, re-administration every 20 minutes. 5 to 20 minutes can be effective. If after 1 hour is still invalid, use of glucose as soon as possible. The dose for children is 5μg/kg.
Vein dropping: diluted infusion of 5% glucose injection. Congestive heart failure, 2.5~7.5mg per hour. Cardiogenic shock; 1~12mg per hour as the medical necessity; sustainable 24 hours intravenous infusion.
Glucagon Chemical Properties
density 1.53±0.1 g/cm3(Predicted)
storage temp. Keep in dark place,Sealed in dry,2-8°C
solubility Practically insoluble in water and in most organic solvents. It is soluble in dilute mineral acids and in dilute solutions of alkali hydroxides.
form powder
Water Solubility Soluble to 1 mg/ml in water
InChIKey MASNOZXLGMXCHN-SXVMFYJYNA-N
More Introduction:https://en.wikipedia.org/wiki/Glucagon
