8-((4-chlorophenyl)thio)cyclic-3--5--gmp and Disease-Models--Animal

Topics: Aging; Animals; Aorta; Cyclic GMP; Disease Models, Animal; Down-Regulation; Endothelium, Vascular; Gene Expression; Male; Metabolic Syndrome; Nitric Oxide; Nitroprusside; Oligopeptides; Oxidative Stress; Rats; Rats, Inbred Strains; Receptor, PAR-2; RNA, Messenger; Thiobarbituric Acid Reactive Substances; Thionucleotides; Trypsin; Vasodilation; Vasodilator Agents

cGMP functions as an extracellular (paracrine) messenger acting at the renal proximal tubule and is an important modulator of pressure-natriuresis (P-N). The signaling pathway activated by cGMP in the tubule cell basolateral membrane remains unknown. We hypothesized that renal interstitial microinfusion of cGMP (50 nmol/kg per minute) or P-N would be accompanied by increased renal protein levels of phospho-Src (Tyr 416) and that the natriuresis would be decreased by Src inhibition. Renal interstitial cGMP-induced natriuresis was blocked by Src inhibitor PP2 (2.0±0.4 versus 0.5±0.01 μEq/g per minute; P<0.001). The inactive analog of PP2, PP3, had no effect on cGMP-induced natriuresis. SU6656, another Src inhibitor, also inhibited cGMP-induced natriuresis (2.0±0.4 versus 1.02±0.01 μEq/g per minute; P<0.001). Renal interstitial cGMP infusion increased phospho-Src protein levels 5.6-fold at 15 minutes and 6.8-fold at 30 minutes compared with vehicle infusion but returned toward basal levels after 60 minutes. PP2 also blunted P-N (3.1±0.1 versus 1.1±0.3 μEq/g per minute; P<0.01) despite a similar increase in blood pressure. PP3 had no effect on P-N. Phospho-Src protein levels increased during P-N in vehicle- (1.8-fold) and PP3-treated (2.1-fold) groups compared with the sham-operated group. PP2 blocked the pressure-induced increase in renal phospho-Src protein levels. PP2 had no effect on renal hemodynamics but decreased both fractional excretion of Na(+) and lithium. Both extracellular cGMP and increased renal perfusion pressure increased renal phospho-Src protein levels and induced natriuresis in an Src-dependent manner, demonstrating that Src is an important downstream signaling molecule for extracellular cGMP-induced natriuresis.

Topics: Animals; Blood Pressure; Cyclic GMP; Disease Models, Animal; Extracellular Fluid; Female; Hypertension; Kidney; Natriuresis; Rats; Rats, Sprague-Dawley; Signal Transduction; Sodium; src-Family Kinases; Thionucleotides

A large body of evidence indicates that nitric oxide (NO) and cGMP contribute to central sensitization of pain pathways during inflammatory pain. Here, we investigated the distribution of cyclic nucleotide-gated (CNG) channels in the spinal cord, and identified the CNG channel subunit CNGA3 as a putative cGMP target in nociceptive processing. In situ hybridization revealed that CNGA3 is localized to inhibitory neurons of the dorsal horn of the spinal cord, whereas its distribution in dorsal root ganglia is restricted to non-neuronal cells. CNGA3 expression is upregulated in the superficial dorsal horn of the mouse spinal cord and in dorsal root ganglia following hindpaw inflammation evoked by zymosan. Mice lacking CNGA3 (CNGA3(-/-) mice) exhibited an increased nociceptive behavior in models of inflammatory pain, whereas their behavior in models of acute or neuropathic pain was normal. Moreover, CNGA3(-/-) mice developed an exaggerated pain hypersensitivity induced by intrathecal administration of cGMP analogs or NO donors. Our results provide evidence that CNGA3 contributes in an inhibitory manner to the central sensitization of pain pathways during inflammatory pain as a target of NO/cGMP signaling.

Topics: Analysis of Variance; Animals; Cyclic GMP; Cyclic Nucleotide-Gated Cation Channels; Disease Models, Animal; Enzyme Inhibitors; Ganglia, Spinal; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Inflammation; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microdissection; Naphthalenes; Natriuretic Peptides; Nitric Oxide; Pain; Pain Measurement; Pain Perception; Peripheral Nervous System Diseases; Physical Stimulation; RNA, Messenger; Signal Transduction; Spinal Cord; Stathmin; Statistics, Nonparametric; Thionucleotides; Triazenes; Vesicular Inhibitory Amino Acid Transport Proteins