guanosine-triphosphate and Hyperglycemia

The sensitivity of components of the adenylate cyclase signaling system (heterotrimer G proteins and adenylate cyclase enzyme) to the regulatory effects of hormones mediated through G proteins (stimulatory effect of isoproterenol and relaxin and inhibitory effects of somatostatin) was decreased in the myocardium of hyperglycemic rats under conditions of transitory hyperglycemia caused by intravenous glucose and in hyperglycemia associated with insulin insufficiency in 24-h type 1 streptozotocin-induced diabetes mellitus. Changes in hormone sensitivity of the adenylate cyclase system were tissue-specific: clearly manifest in the myocardium, minor in skeletal muscles, and virtually absent in the brain of hyperglycemic rats. The main disorders of this system in the myocardium were observed at the stage of hormone receptor coupling with G proteins, which was seen from reduced stimulatory effect of GppNHp on adenylate cyclase activity and attenuation of the regulatory effect of hormones on adenylate cyclase enzyme and G proteins functionally coupled with it.

Topics: Adenosine Triphosphate; Adenylyl Cyclases; Animals; Brain; Cells; Cyclic AMP; Diabetes Mellitus, Type 1; GTP-Binding Proteins; Guanosine Triphosphate; Hyperglycemia; In Vitro Techniques; Isoproterenol; Male; Muscle, Skeletal; Protein Binding; Rats; Rats, Wistar; Receptors, Peptide; Relaxin; Somatostatin; Streptozocin

Topics: Adenylyl Cyclases; Animals; Cell Membrane; Enzyme Activation; Fluorides; Glucagon; Guanosine Triphosphate; Guanylyl Imidodiphosphate; Hyperglycemia; Liver; Mice; Mice, Obese

Topics: Adenosine Triphosphate; Animals; Bucladesine; Butyrates; Cyclic AMP; Cyclic GMP; Cytosine Nucleotides; Drug Synergism; Female; Glucose; Guanosine Triphosphate; Hyperglycemia; In Vitro Techniques; Inosine Nucleotides; Insulin; Insulin Antibodies; Insulin Secretion; Iodine Radioisotopes; Islets of Langerhans; Mice; Nucleotides, Cyclic; Obesity; Uracil Nucleotides