Dissociation between plasma, urine, and renal papillary cyclic AMP content following vasopressin and DDAVP

1979 ◽  
Vol 237 (3) ◽  
pp. F218-F225 ◽  
Author(s):  
M. J. Bia ◽  
S. Dewitt ◽  
J. N. Forrest
Keyword(s):  
Cyclic Amp ◽  
Urine Osmolality ◽  
Brattleboro Rats ◽  
Renal Papilla ◽  
Brattleboro Rat ◽  
Clearance Studies ◽  
Urinary Cyclic Amp ◽  
Stimulation Of

The effects of in vivo physiologic doses of vasopressin and 1-deamino-8-D-arginine vasopressin (DDAVP) on the cyclic AMP content of plasma, urine, and renal papillary tissue were determined in the ADH-deficient Brattleboro rat. During clearance studies, plasma cyclic AMP concentrations and both total and nephrogenous urinary cyclic AMP excretion in vasopressin- and DDAVP-treated rats were similar to the values in time-matched controls. In contrast, in situ renal papillary cyclic AMP content was higher (P less than 0.001) in both vasopressin- (35.7 +/- 3.6 pmol/mg protein) and DDAVP- (29.7 +/- 2.2 pmol/mg protein) treated rats compared to controls (15.1 +/- 1.3 pmol/mg protein). Endogenous stimulation of vasopressin by dehydration in normal rats increased both papillary cyclic AMP content (27.1 +/- 2.7 pmol/mg protein) and urine osmolality, whereas no change in papillary cyclic AMP was observed following dehydration in Brattleboro rats (13.6 +/- 0.8 pmol/mg protein) despite an increase in urine osmolality. The results demonstrate that changes in cyclic AMP following in vivo vasopressin are best demonstrated by measurement of in situ cyclic AMP content of the renal papilla, whereas total urinary cyclic AMP and nephrogenous cyclic AMP are not useful indices of tubular sensitivity to this hormone.

scholarly journals Stimulatory effect of prostaglandin E2 on 1α,25-dihydroxyvitamin D3 synthesis in rats

1983 ◽  
Vol 216 (1) ◽  
pp. 237-240 ◽  
Author(s):  
M Yamada ◽  
T Matsumoto ◽  
N Takahashi ◽  
T Suda ◽  
E Ogata
Keyword(s):  
Vitamin D ◽  
Cyclic Amp ◽  
Prostaglandin E2 ◽  
Vitamin D3 ◽  
Arterial Infusion ◽  
Dihydroxyvitamin D3 ◽  
Significant Stimulation ◽  
Urinary Cyclic Amp ◽  
Stimulation Of

The effect of prostaglandin E2 on accumulation in plasma of 1 alpha,25-dihydroxy[3H]vitamin D3 from 25-hydroxy[3H]vitamin D3 was studied in vivo using vitamin D-deficient thyroparathyroidectomized rats. Intra-arterial infusion of 10-50 micrograms of prostaglandin E2/h caused a significant stimulation of 1 alpha,25-dihydroxy[3H]vitamin D3 production. No significant changes in plasma Ca2+ and Pi concentrations or urinary cyclic AMP excretion were observed after prostaglandin E2 infusion. Theophylline did not enhance the effect of a submaximal dose of prostaglandin E2 on 1 alpha,25-dihydroxy[3H]vitamin D3 production. These data indicate that prostaglandin E2 stimulates plasma accumulation of 1 alpha,25-dihydroxy[3H]vitamin D3 independent of the adenylate cyclase/cyclic AMP system, and suggest that prostaglandin E2 has a modulatory role in the regulation of 25-hydroxyvitamin D3 1 alpha-hydroxylase in the kidney.

Metabolic Support of Chloride-dependent Short-circuit Current Across Locust Rectum

1982 ◽  
Vol 99 (1) ◽  
pp. 349-362
Author(s):  
M. CHAMBERLIN ◽  
J. E. PHILLIPS
Keyword(s):  
Cyclic Amp ◽  
Short Circuit ◽  
Malpighian Tubule ◽  
Short Circuit Current ◽  
Metabolic Substrates ◽  
Endogenous Substrates ◽  
Tubule Fluid ◽  
Substrate Source ◽  
Stimulation Of

1. Recta of desert locusts were short-circuited and depleted of endogenous substrates by exposing them to saline containing cyclic AMP but no metabolites. Individual substrates were then added to substrate-depleted recta and the change in short-circuit current (Isc) monitored. 2. Proline or glucose (50 mM) caused by far the largest increase in Isc of all substrates tested. Stimulation of the Isc by proline was not dependent upon external sodium, but did require external chloride. 3. Physiological levels of proline also caused a large increase in Isc, while physiological levels of glucose produced a much smaller stimulation. Over 90% of the proline-dependent Isc stimulation can be produced by adding 15 mM proline solely to the lumen side of the tissue. 4. These results are discussed with regard to rectal oxidative metabolism and availability of metabolic substrates in vivo. High levels of proline in Malpighian tubule fluid are probably the major substrate source for rectal Cl−transport. Note:

Possible role of cyclic GMP in stimulus-secretion coupling by salt gland of the duck

1979 ◽  
Vol 237 (5) ◽  
pp. C200-C204 ◽  
Author(s):  
D. J. Stewart ◽  
J. Sax ◽  
R. Funk ◽  
A. K. Sen
Keyword(s):  
Cyclic Amp ◽  
Guanylate Cyclase ◽  
Cyclic Gmp ◽  
Salt Gland ◽  
Domestic Ducks ◽  
Stimulus Secretion Coupling ◽  
Stimulation Of

Stimulation of salt galnd secretion in domestic ducks in vivo increased the cyclic GMP concentration of the tissue, but had no effect on cyclic AMP levels. Methacholine, which is known to stimulate sodium transport by the glands both in vivo and in vitro, stimulated ouabain-sensitive respiration in salt gland slices. Cyclic GMP stimulated ouabain-sensitive respiration to the same extent as methacholine. Guanylate cyclase stimulators, hydroxylamine and sodium azide, also stimulated ouabain-sensitive respiration. The stimulation of ouabain-sensitive respiration by methacholine was blocked either by atropine or by removal of calcium from the incubation medium. The stimulation of ouabain-sensitive respiration by cyclic GMP still occurred in the absence of calcium. The above observations seem to indicate that cyclic GMP acts as a tertiary link in the process of stimulus-secretion coupling in the tissue.

Localization and In Situ Activities of Homoacetogenic Bacteria in the Highly Compartmentalized Hindgut of Soil-Feeding Higher Termites (Cubitermes spp.)

1999 ◽  
Vol 65 (10) ◽  
pp. 4497-4505 ◽  
Author(s):  
Anne Tholen ◽  
Andreas Brune
Keyword(s):  
Detection Limit ◽  
Companion Paper ◽  
Homoacetogenic Bacteria ◽  
Appl Environ ◽  
Partial Pressures ◽  
Almost All ◽  
Stimulation Of

ABSTRACT Methanogenesis and homoacetogenesis occur simultaneously in the hindguts of almost all termites, but the reasons for the apparent predominance of methanogenesis over homoacetogenesis in the hindgut of the humivorous species is not known. We found that in gut homogenates of soil-feeding Cubitermes spp., methanogens outcompete homoacetogens for endogenous reductant. The rates of methanogenesis were always significantly higher than those of reductive acetogenesis, whereas the stimulation of acetogenesis by the addition of exogenous H2 or formate was more pronounced than that of methanogenesis. In a companion paper, we reported that the anterior gut regions of Cubitermes spp. accumulated hydrogen to high partial pressures, whereas H2 was always below the detection limit (<100 Pa) in the posterior hindgut, and that all hindgut compartments turned into efficient H2 sinks when external H2 was provided (D. Schmitt-Wagner and A. Brune, Appl. Environ. Microbiol. 65:4490–4496, 1999). Using a microinjection technique, we found that only the posterior gut sections P3/4a and P4b, which harbored methanogenic activities, formed labeled acetate from H14CO3 −. Enumeration of methanogenic and homoacetogenic populations in the different gut sections confirmed the coexistence of both metabolic groups in the same compartments. However, the in situ rates of acetogenesis were strongly hydrogen limited; in the P4b section, no activity was detected unless external H2 was added. Endogenous rates of reductive acetogenesis in isolated guts were about 10-fold lower than the in vivo rates of methanogenesis, but were almost equal when exogenous H2 was supplied. We conclude that the homoacetogenic populations in the posterior hindgut are supported by either substrates other than H2 or by a cross-epithelial H2transfer from the anterior gut regions, which may create microniches favorable for H2-dependent acetogenesis.

In vivo modulation by α2-adrenoceptors of adrenal catecholamine release in the anaesthetized dog

1988 ◽  
Vol 66 (3) ◽  
pp. 380-384 ◽  
Author(s):  
Sylvain Foucart ◽  
Jacques de Champlain ◽  
Reginald Nadeau
Keyword(s):  
Electrical Stimulation ◽  
Splanchnic Nerve ◽  
Catecholamine Release ◽  
Agonist Stimulation ◽  
Control Stimulation ◽  
Anaesthetized Dog ◽  
Splanchnic Nerve Stimulation ◽  
Stimulation Of

In this study, the reversal of the potentiating effect of idazoxan, a selective α2-antagonist, on adrenal catecholamine release elicited by splanchnic nerve stimulation in anaesthetized and vagotomized dogs, was investigated with the use of oxymetazoline, a selective α2-agonist. Stimulation of the left splanchnic nerve (5.0-V pulses of 2 ms duration for 3 min at a frequency of 2 Hz) was applied before and 20 min after the i. v. injection of each drug. Blood samples were collected in the adrenal vein before and at the end of each stimulation. The results show that the release of catecholamines induced by electrical stimulation was potentiated by 50% after idazoxan injection (0.1 mg/kg). This enhanced response was significantly antagonized by the subsequent injection of oxymetazoline (2 μg/kg). The α2-modulating effect appears to be related to the amount of catecholamines released during the stimulation, since by subgrouping of the data on the basis of the degree of potentiation by idazoxan, it was observed that this drug was more efficient when catecholamine release was higher during control stimulation. In contrast, the reversing effect of oxymetazoline was found to be more pronounced when catecholamine release was lower. These results thus suggest that the sensitivity of the α2-adrenoceptor mechanism may depend upon the in situ concentration of adrenal catecholamine release during electrical stimulation and that the potentiating effect of α2-blockade can be reversed by activation of those receptors by a selective α2-agonist.

scholarly journals Alterations in the binding site of the cyclic AMP receptor protein at the Escherichia coli galactose operon regulatory region

1988 ◽  
Vol 253 (3) ◽  
pp. 809-818 ◽  
Author(s):  
K Gaston ◽  
B Chan ◽  
A Kolb ◽  
J Fox ◽  
S Busby
Keyword(s):  
Escherichia Coli ◽  
Cyclic Amp ◽  
Binding Site ◽  
Consensus Sequence ◽  
Regulatory Region ◽  
Receptor Protein ◽  
Binding Assays ◽  
Cyclic Amp Receptor Protein ◽  
Stimulation Of

Gene manipulation techniques have been used to alter the binding site for the cyclic AMP-cyclic AMP receptor protein complex (cAMP-CRP) at the regulatory region of the Escherichia coli galactose (gal) operon. The effects of these changes on CRP-dependent stimulation of expression from the galP1 promoter in vivo have been measured, and gel binding assays have been used to measure the affinity of cAMP-CRP for the modified sites. Firstly we have deleted progressively longer sequences from upstream of the gal CRP site in order to locate the functional limit of the site. A deletion to -49, removing the first base that corresponds to the consensus sequence for a CRP binding site, is sufficient to reduce CRP binding and block CRP-dependent stimulation of P1. Secondly, we used synthetic oligonucleotides to invert the asymmetric nucleotide sequence at the gal CRP binding site or to make the sequence symmetric. Inversion of the site has little effect on CRP binding, the architecture of open complexes at P1 revealed by DNAase I footprinting, or the stimulation of transcription from P1. Making the site symmetric increases the affinity for CRP by over 50-fold and leads to increased transcription from P1, whilst hardly altering the DNAase I footprint of open complexes. Our results confirm that the strength of binding of CRP depends on the nature of the site and show that it is this that principally accounts for differences in CRP-dependent stimulation of transcription.

scholarly journals Regulation of the synthesis of lutropin-induced protein in rat testis Leydig cells

1978 ◽  
Vol 170 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Felix H. A. Janszen ◽  
Brian A. Cooke ◽  
Maria J. A. Van Driel ◽  
Henk J. Van Der Molen
Keyword(s):  
Protein Synthesis ◽  
Cyclic Amp ◽  
Leydig Cells ◽  
Actinomycin D ◽  
Polyacrylamide Gel Electrophoresis ◽  
Phosphodiesterase Inhibitor ◽  
Dibutyryl Cyclic Amp ◽  
Rat Testis ◽  
Stimulation Of

The mechanism of action of lutropin on the stimulation of the synthesis of a specific lutropin-induced protein in rat testis Leydig cells was investigated. Lutropin-induced protein has a mol.wt. of approx. 21000 and is detected by labelling the Leydig-cell proteins with [35S]methionine, followed by separation by polyacrylamide-gel electrophoresis and radioautography of the dried gel. The incorporation of35S into lutropin-induced protein was used as an estimate for the synthesis of the protein. Incubation of Leydig cells with dibutyryl cyclic AMP or cholera toxin also resulted in the stimulation of synthesis of the protein. Synthesis of lutropin-induced protein, when maximally stimulated with 100ng of lutropin/ml, could not be stimulated further by addition of dibutyryl cyclic AMP. Addition of 3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor, further increased synthesis of the protein in the presence of a submaximal dose of lutropin (10ng/ml) but not in the absence of lutropin or with maximal amounts of lutropin (100 and 1000ng/ml). Actinomycin D prevented the effect of lutropin on the stimulation of lutropin-induced protein synthesis when added immediately or 1h after the start of the incubation, but not when added after 5–6h. This is interpreted as reflecting that, after induction of mRNA coding for lutropin-induced protein, lutropin had no influence on the synthesis of the protein in the presence of actinomycin D. Synthesis of the protein was also stimulated in vivo by injection of choriogonadotropin into rats 1 day after hypophysectomy, and the time course of this stimulation of lutropin-induced protein synthesis in vivo was similar to that obtained by incubating Leydig cells in vitro with lutropin. From these results it is concluded that stimulation of lutropin-induced protein synthesis by lutropin is most probably mediated by cyclic AMP and involves synthesis of mRNA.

In vivo IIX and IIB fiber recruitment in gastrocnemius muscle of the rat is compartment related

1996 ◽  
Vol 81 (2) ◽  
pp. 933-942 ◽  
Author(s):  
C. J. De Ruiter ◽  
P. E. Habets ◽  
A. de Haan ◽  
A. J. Sargeant
Keyword(s):  
Cross Sections ◽  
Gastrocnemius Muscle ◽  
Periodic Acid ◽  
Medial Gastrocnemius ◽  
Periodic Acid Schiff ◽  
Fast Twitch ◽  
Medial Gastrocnemius Muscle ◽  
Stimulation Of

The purpose of the present study was to investigate to what extent fast-twitch IIX and IIB fiber recruitment was related to the natural existing muscle compartments (subvolumes of muscle innervated by different primary nerve branches) in rat medial gastrocnemius. Three groups (n = 6) of rats trotted on a motor-driven treadmill (20 degrees incline) at different speeds. A fourth group served as controls, and a fifth group received in situ electrical stimulation of all medial gastrocnemius muscle fibers. Postexercise glycogen levels (periodic acid-Schiff staining intensities) were made. Running caused more and in situ stimulation caused less glycogen breakdown in the proximal IIX and IIB fibers compared with the fibers of the same type in the most distal compartment. Furthermore, the boundaries of the most distal compartment could often be recognized in the periodic acid-Schiff-stained cross sections. It was concluded that during running the proximal IIX and IIB fibers were recruited to a greater extent (and at lower treadmill speeds) compared with the distal IIX and IIB fibers, respectively.

EFFECTS OF ACTH AND ITS O-NITROPHENYL SULPHENYL DERIVATIVE ON ADRENOCORTICAL FUNCTION IN VIVO

1976 ◽  
Vol 82 (3) ◽  
pp. 587-599 ◽  
Author(s):  
J. Ramachandran ◽  
Y. C. Kong ◽  
Susanna Liles
Keyword(s):  
Cyclic Amp ◽  
Adrenal Weight ◽  
Adrenocortical Function ◽  
Tryptophan Residue ◽  
Adult Rats ◽  
Corticosterone Concentration ◽  
Hypophysectomized Rats ◽  
Stimulation Of

ABSTRACT Both ACTH and NPS-ACTH in which the single tryptophan residue of the hormone is modified were able to stimulate adrenal corticosterone concentration to the same extent in hypophysectomized rats, although a higher dose of NPS-ACTH was required. ACTH stimulated adrenal cyclic AMP levels 120-fold in hypophysectomized rats whereas NPS-ACTH caused a marginal increase. In the case of ACTH, low doses of the hormone capable of producing maximal stimulation of corticosterone synthesis did not produce any detectable change in cyclic AMP concentration. The rates of secretion of corticosterone induced by ACTH and NPS-ACTH in vivo were the same. NPS-ACTH was found to be 1.2% as potent as ACTH. The role of cyclic AMP in adrenal repair was investigated by administering equipotent doses of ACTH or NPS-ACTH to hypophysectomized rats. In adult rats both failed to produce a significant increase in adrenal weight. Adrenal function (measured by responsiveness to exogenous ACTH in vitro) was restored by NPS-ACTH but not to the same degree as ACTH. In hypophysectomized weanling rats, ACTH produced a small but significant increase in adrenal weight but NPS-ACTH did not. These results suggest that an increase in adrenal cyclic AMP may not be obligatory for the stimulation of steroidogenesis by ACTH and that some of the trophic actions of the hormone may be mediated by cyclic AMP.

Renal cyclic AMP accumulation and adenulate cyclase stimulation by erythropoietic agents

1975 ◽  
Vol 229 (5) ◽  
pp. 1387-1392 ◽  
Author(s):  
GM Rodgers ◽  
JW Fisher ◽  
WJ George
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Regional Distribution ◽  
Renal Medulla ◽  
Iron Incorporation ◽  
Erythropoietin Production ◽  
Cyclic Amp Accumulation ◽  
Stimulation Of

The regional distribution of cyclic AMP in the kidney was determined following erythropoietic stimulation with hypoxia and cobalt. Following these stimuli, increases in renal cyclic AMP concentrations were restricted to the cortex. The basis for this localization in the case of cobalt treatment was found to reside in the stimulation of renal cortical adenylate cyclase activity in vitro by concentrations of cobalt similar to those found in vivo. The level of cobalt in the cortex after cobalt treatment was found to approach 500 mumol/kg of tissue, whereas no detectable levels of cobalt were found in the renal medulla. Additionally, other agents such as parathyroid hormone and lactic acid, that are known to lack stimulatory effects on medullary adenylate cyclase, were found to stimulate the cortical enzyme. This stimulation of renal cortical adenylate cyclase correlates with enhanced erythropoiesis as demonstrated by increased radiolabeled iron incorporation into erythrocytes. These results support previous reports which suggest that renal cortical cyclic AMP mediates erythropoietin production in response to erythropoietically active agents.

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