Action of serotonin (5-hydroxytryptamine) on cyclic nucleotides in glomeruli of rat renal cortex

Abstract

Serotonin (5-hydroxytryptamine) is known to influence glomerular function and may have an important role in the pathogenesis of glomerulopathies. Because serotonin acts in nonrenal tissues through mediation of cyclic nucleotides, we investigated in vitro its effect on cAMP and cyclic guanosine monophasphate (cGMP) in tissue slices and isolated glomeruli from rat kidney. Serotonin increased cAMP 161 +/- 35% but not cGMP in renal cortex; it had no effect on cyclic nucleotides in medulla and papilla. In isolated glomeruli, serotonin elicited a dose-dependent (in the range of 10-7 to 10-4 M) increase in cAMP; the maximum increase over basal values was 376 +/- 45%. Serotonin increased cAMP either in the presence or in the absence of a cAMP phosphodiesterase inhibitor. In tubular fraction, serotonin elevated cAMP to a much lesser degree (82 +/- 15%). Neither in glomeruli nor in tubules did cGMP concentrations change in response to serotonin, but carbamylcholine, a known cGMP agonist, significantly increased cGMP concentrations. The increase in cAMP in response to serotonin was blocked (greater than 85% inhibition) by equimolar concentrations of serotonin antagonists methysergide and cinanserine. Results of this study demonstrate that interaction of serotonin with receptors in the kidney, particularly in the glomeruli, cause a striking increase in cAMP concentrations without detectable changes in cGMP concentrations. These findings suggest that serotonin, either synthesized in the kidney or released locally from platelets aggregated in glomeruli (for example, in association with immunopathologic injury) may exert of modulate its physiologic or pathologic effects via mediation of cAMP.

Cellular Action of Vasopressin in Medullary Tubules of Mice with Hereditary Nephrogenic Diabetes Insipidus

“…The content of cAMP was determined by RIA as described in detail in our recent communications (26,27). Samples, dissolved in acetate buffer (see above), and cAMP standards were first acetylated as described by Frandsen and Krishna (28), in a way analogous to our previous study (26).…”

“…Acetylated samples and cAMP standards were incubated with anti-cAMP antibodies and 1251-succinyl-cyclic AMP methyl-ester for 16-24 h at 40C. Free and bound antigens were separated by centrifugation at 7,000 g for 20 min (26,27). Radioactivity of the samples was counted in a Searle analytical gamma counter, model 1285 (Searle Radiographics Inc., Des Plaines, Ill.).…”

“…Frozen mierodissected tubule samples were dissolved in 10 Al of 1% sodium dodecyl sulfate (7,23,26,27), and protein content was detennined by a modification of the colorimetric method of Lowry (29), similar to that used for protein determination in micropuncture samples (30). Final volume was 90 jAl; using this modification for very small samples, quantities as low as 0.2 jxg protein/sample could be accurately determined.…”

Effect of enzymatically generated reactive oxygen metabolites on the cyclic nucleotide content in isolated rat glomeruli.

“…Both these local hormones are produced in the glomeruli (4, 5), and both have been shown to increase cyclic AMP content in glomeruli (2,8,37). In addition, kidney has been shown to synthesize serotonin (6) and serotonin has been shown to cause a marked increase in the cyclic AMP content in glomeruli (7). As an initial approach, we therefore utilized PG synthesis inhibitors, histamine antagonist, and serotonin antagonist to examine the mechanisms by which reactive oxygen metabolites increase cyclic AMP content in glomeruli (Table V).…”

“…Incubations of tissue preparation and analyses of cyclic nucleotides were conducted with only minor modifications to the method used in our previous studies (7). Freshly prepared glomeruli (4-6 mg, wet weight) and tubules (8-12 mg, wet weight) were distributed randomly (in duplicate or triplicate for each experimental condition) into 10-ml glass homogenizer tubes (size A, Thomas Scientific Products, Philadelphia, PA), kept in crushed ice at 0°C, and aliquots for protein determination were taken.…”