Forskolin increases osmotic water permeability of rabbit cortical collecting tubule

Forskolin is a unique diterpene that may directly activate the catalytic subunit of adenylate cyclase. We therefore examined the effect of 50 microM forskolin on osmotic water permeability in rabbit cortical collecting tubules perfused in vitro. Forskolin increased net volume flux (Jv, from 0.30 to 1.22 nl/mm/min, P less than 0.02) in all tubules. The hydro-osmotic effect of forskolin was similar with respect to magnitude and time course to that produced by a maximal dose (250 microU/ml) of arginine vasopressin. An additive effect on Jv and Lp was not observed when maximal concentrations of forskolin and arginine vasopressin were given simultaneously. The compound d(CH2)5Tyr(Et) VAVP, which noncompetitively inhibits the vasopressin receptor, significantly reduced collecting tubular hydro-osmotic response to arginine vasopressin. In contrast, the hydro-osmotic response to forskolin was maintained in the presence of d(CH2)5 Tyr(Et)VAVP. However, the hydro-osmotic response to forskolin could be inhibited by 1.0 microM guanine 5'-(beta,gamma-imido) triphosphate (GppNHp) and by the calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). These results demonstrate that forskolin exerts an hydro-osmotic effect in the mammalian nephron which occurs independent of the vasopressin receptor. Guanine nucleotide regulatory proteins may modulate the osmotic water permeability effect of forskolin. Finally, calmodulin is required for full expression of the effect of forskolin to increase osmotic water flux.

Do alcoholic Korsakoff's syndrome patients acquire affective reactions?

In this study we report two experiments that investigate the acquisition of affective reactions. In Experiment 1, unfamiliar melodies were played to Korsakoff's syndrome patients and alcoholic and nonalcoholic control subjects who were matched with them according to age and education. Following a retention interval of 5 min, subjects received a preference test on old and new melodies. Korsakoff's syndrome patients showed the same increase in preference for old melodies as a consequence of prior exposures as control subjects did, but their recognition of melodies was significantly impaired in comparison with controls. In Experiment 2, the same subjects saw photographs of two men. Fictional biographical information depicted one as a "good guy" and the other as a "bad guy." After a retention interval of approximately 20 days, Korsakoffs recalled virtually none of the biographical information; however, 78% preferred the good guy, and impression ratings were less favorable for the bad guy. Korsakoff patients developed preferences and impressions even though they did not have voluntary access to the information on which the preferences were based. However, their impression ratings were less extreme than those of controls. The pattern of results of the two studies is discussed in terms of Johnson's (1983) MEM model of memory.

Do alcoholic Korsakoff's syndrome patients acquire affective reactions?

In this study we report two experiments that investigate the acquisition of affective reactions. In Experiment 1, unfamiliar melodies were played to Korsakoff's syndrome patients and alcoholic and nonalcoholic control subjects who were matched with them according to age and education. Following a retention interval of 5 min, subjects received a preference test on old and new melodies. Korsakoff's syndrome patients showed the same increase in preference for old melodies as a consequence of prior exposures as control subjects did, but their recognition of melodies was significantly impaired in comparison with controls. In Experiment 2, the same subjects saw photographs of two men. Fictional biographical information depicted one as a "good guy" and the other as a "bad guy." After a retention interval of approximately 20 days, Korsakoffs recalled virtually none of the biographical information; however, 78% preferred the good guy, and impression ratings were less favorable for the bad guy. Korsakoff patients developed preferences and impressions even though they did not have voluntary access to the information on which the preferences were based. However, their impression ratings were less extreme than those of controls. The pattern of results of the two studies is discussed in terms of Johnson's (1983) MEM model of memory.

The cyclic AMP system in the inner medullary collecting duct of the potassium-depleted rat

The present study was undertaken to investigate the cyclic AMP system in the isolated inner medullary collecting tubule (IMCT) of hypokalemic (HK) rats. In situ incubation of IMCT with 10(-7) M arginine vasopressin (AVP) at 300 mOsm/kg H2O in control normokalemic rats increased cyclic AMP content (fmoles/mm) from 5.68 +/- 1.41 to 30.3 +/- 5.31 (P less than 0.001). In HK rats the increase in cyclic AMP was blunted from 7.18 +/- 2.0 to 14.78 +/- 3.14 fmoles/mm (P less than 0.05 compared to controls). No such blunting was observed in the outer medullary collecting duct of hypokalemic rats, but was seen in the IMCT when studied at 800 (P less than 0.05), 1200 (P less than 0.01), and 2000 mOsm/kg H2O (P less than 0.05). The increase in cyclic AMP was also blunted in IMCT of HK rats not allowed to become polyuric or polydipsic by pair-watering studied at 300, 800, and 1200 mOsm/kg H2O. To define the process responsible for the failure to normally increase cyclic AMP in HK, adenylate cyclase activity (AC) was determined at 800 mOsm/kg H2O. While basal AC was not different, the response to all concentrations of AVP between 10(-10) and 10(-6) M was markedly depressed in tubules from HK rats. In contrast AC response to 10(-2) M NaF was not different in IMCT of normokalemic and HK rats. While the abnormal cyclic AMP content with AVP could be explained by abnormal generation, a contribution of increased metabolism was also sought.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of escape from desmopressin in the rat

The mechanism(s) of renal escape from the hydro-osmotic effect of vasopressin is unknown. We therefore studied escape in conscious, unrestrained rats receiving continuous intravascular infusions of 1-deamino-8-arginine-vasopressin (desmopressin) and hypotonic fluid over 5 days. Escape from desmopressin started 8 hours after exposure and was characterized by a progressive increase in urine flow and decreases in urine osmolality and free water reabsorption. When positive water balance was prevented by matching the rate of infusion of hypotonic fluid to urine flow while maintaining the dose of desmopressin constant, escape did not occur. This suggested that water retention, rather than chronic exposure to desmopressin, mediated the escape. To elucidate the mechanism whereby water retention induces escape from desmopressin, urinary prostaglandin E2 excretion was measured and found to be increased concomitant with the onset of escape. Prevention of this increase in urinary prostaglandin E2 excretion with indomethacin resulted in additional water retention and a delay in the onset of escape. During the maintenance of escape, after significant water retention occurred, increases in mean arterial pressure, renal blood flow, and glomerular filtration rate were observed. Renal interstitial solute concentration remained constant through escape. Basal and vasopressin-stimulated collecting tubular and thick ascending limb adenylate cyclase did not differ when control and escape animals were compared. These results suggest that enhanced renal synthesis of prostaglandin E2 facilitates the early phase of escape; later, water retention results in plasma volume expansion with increases in cardiac index, arterial pressure, renal blood flow, and glomerular filtration rate. These systemic and renal hemodynamic alterations may be important in maintaining escape from desmopressin.

Further in vivo evidence for antagonist-to-antidiuretic action of arginine vasopressin

The effect of a new arginine vasopressin (AVP) analogue, [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid), 2-O-ethyltyrosine, 4-valine]AVP or d(CH2)5Tyr(Et)VAVP, was examined on exogenous and endogenous AVP in the conscious rat. An intravenous injection of 8 micrograms/kg body wt of the AVP analogue completely blocked the antidiuretic effect of exogenous AVP (4 ng/kg body wt iv). Similarly, 8 micrograms/kg of the AVP analogue totally abolished the antidiuretic effect of infused AVP (0.1 mU X kg-1 X min-1) in the homozygous Brattleboro rats with central diabetes insipidus. The antagonism of this antidiuretic effect of exogenous AVP occurred in the absence of changes in urinary solute excretion, glomerular filtration rate (GFR), and mean arterial pressure. Intraperitoneal administration of the AVP analogue (30 micrograms/kg body wt) decreased the mean urinary osmolality in rats after 24 h of fluid deprivation from 3,098 +/- 140 to 797 +/- 155 mosmol/kg H2O (P less than 0.001). The duration of the antagonism of endogenous AVP was approximately 4.5 h. The antagonism of AVP was not dependent on the vascular properties of AVP, since the AVP analogue also blocked the antidiuretic effect of exogenous 1-deamino-8-D-AVP (DDAVP), an AVP analogue with negligible vascular properties. These in vivo results therefore indicate that d(CH2)5Tyr(Et)VAVP is a specific antagonist of the hydrosmotic effect of exogenous and endogenous AVP. In contrast to some previous analogues, this effect of the AVP analogue occurred in the absence of any known diuretic factors including an increase in GFR, solute excretion, and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritive quality of leaf proteins coagulated at different pH

Leaf proteins obtained by coagulation at different pH were examined for their chemical composition and nutritional quality. Green juice was extracted from alfalfa, red clover, Italian ryegrass and oats and leaf protein was coagulated by heating the juice after adjusting the pH to 4 or 8-8.5, or without any adjustment of the pH (about pH 6). The mild alkaline juice from Italian ryegrass and oats did not cause the satisfactory coagulation but it was achieved with the addition of Ca salt to the juice before heating. There were no important differences in the amino acid compositions of the leaf proteins coagulated at different pH. Crude ash, Ca and Mg contents increased with an increase in pH of coagulation and the protein coagulated at pH 8 had remarkably high contents of crude ash, Ca, Mg, Na and P in each crop. The leaf protein coagulated at pH 6, on the contrary, had a high content of true protein and low contents of nitrogen free extracts and nucleic acid as compared with those at pH 4 and 8. The pH of coagulation of leaf protein from alfalfa and red clover had no effect on the nutritional quality of the respective proteins. In Italian ryegrass and oats, however, the leaf protein coagulated at pH 8 was found to be nutritionally inferior to those coagulated at a lower pH. The data presented in this work support that in general, the leaf protein produced by heating the green juice without any adjustment of pH may be suitable for protein resources because of its desirable properties, i.e. high true protein content and good nutritional quality.

Sulphide as an inhibitor and electron donor for the cytochrome c oxidase system

Anomalies both kinetic and equilibrium in nature are described for the inhibition of cytochrome c oxidase activity by sulphide in the isolated enzyme and in submitochondrial particles. These anomalies are related to the involvement of more than 1 mol of sulphide in the blockage of one cytochrome aa3 centre. Sulphide reduces resting cytochrome a3, a reaction that results in oxygen uptake and the loss of a sulphide molecule. Sulphide can also reduce cytochromes c and a; in the former case, a part of the one-equivalent oxidation product, presumed to be the SH radical, reacts with oxygen. Such oxygen uptake is also seen under aerobic conditions when ferricyanide reacts with sulphide. Three phases are identified in the inhibitory interaction of sulphide with the cytochrome c oxidase enzyme itself: an initial rapid reaction involving sulphide oxidation, oxygen uptake, and conversion of cytochrome aa3 into the low-spin "oxyferri" form; a subsequent step in which sulphide reduces cytochrome a; and the final inhibitory step in which a third molecule of sulphide binds the a3 iron centre in the cytochrome a2+ a3 3+ (oxy) species to give cytochrome a2+ a3 3+ H2S. the initial events parallel some of the events in the interaction of the cytochrome c-cytochrome aa3 system with monothiols; the final inhibitory event resembles that with cyanide.

Use of Denver shunt in recurrent hepatic hydrothorax

A 49-year-old woman with alcoholic cirrhosis was hospitalized for severe respiratory distress. A moderate amount of ascites was noted on physical examination, and the right hemithorax was completely opacified on the chest x-ray film. Thoracentesis was performed, and a follow-up chest x-ray film showed marked reduction of pleural effusion. Two days later the patient again was in respiratory distress, and a chest tube was inserted. On the tenth hospital day, a peritoneovenous (Denver) shunt was inserted and the chest tube was removed. Follow-up chest x-ray films showed almost complete resolution of pleural effusion, and the patient has remained free of symptoms. When hepatic hydrothorax does not respond to conventional therapy, we believe aggressive treatment with a Denver shunt may be successful. To our knowledge this procedure has been performed successfully in only one other patient. Further study is needed to assess its value as a possible alternative method of treatment.

Effect of potassium depletion on the vasopressin-sensitive cyclic AMP system in rat outer medullary tubules

The effects of PDN on VP-sensitive cAMP metabolism were examined in MCT and MAL microdissected from the rat kidney. VP-sensitive adenylate cyclase activity was significantly reduced (delta -46%; p less than 0.05) in MAL of PDN rats but, in sharp contrast, was significantly increased (delta +79%; p less than 0.02) in MCT of PDN rats compared to controls. cAMP phosphodiesterase activity was significantly increased in both MAL (delta +59%; p less than 0.005) and MCT (delta +79%; p less than 0.001) of PDN rats compared to controls. The increase in cAMP accumulation in MAL measured in response to VP in intact tubules did not differ between PDN and controls, whereas cAMP accumulation in response to VP was significantly higher (delta +127%; p less than 0.001) in MCT of PDN rats compared to controls. The present results would indicate that the observed in vivo resistance to the antidiuretic effect of VP that occurs in PDN is not due to an impairment in VP-sensitive cAMP accumulation in MCT, but would rather suggest that a defect exists at a cellular step subsequent to cAMP generation. In addition, our results illustrate that the extent and directionality of in situ accumulation of cAMP measured in intact tubules cannot always be predicted from rhe activities of enzymes controlling its synthesis and degradation (adenylate cyclase and cAMP phosphodiesterase), which are measured in vitro in disrupted tubules.

Oxidation of sulphide by cytochrome aa3

The effectiveness of H2S as an inhibitor of cytochrome c oxidase increase (Ki decreases) with sulphide concentration. A spectroscopic change in cytochrome aa3 is induced aerobically by sulphide at the same rate as that calculated for inhibition. The initial spectroscopic product is not inhibited, but an 'oxygenated' (oxyferri) form of the enzyme. Stoichiometric sulphide addition to cytochrome aa3 under anaerobic conditions produces another low-spin form of the enzyme; subsequent admission of oxygen gives rise to the 607 nm compound. At high enzyme levels sulphide itself acts as a substrate measured polarographically, with an oxygen uptake proportional to the amount of sulphide added. Binding of sulphide to ferric enzyme probably causes reduction at the oxygen-sensitive a3-Cu centre, which is followed aerobically by reoxidation to the oxyferri state via the 607 nm intermediate. A stable sulphide complex is formed only after the reduction of cytochrome a; but once formed this inhibited species is retained if cytochrome a is reoxidized.

Membrane immunoglobulins of spontaneous B lymphomas of aged BALB/c mice

Four cell lines derived from spontaneous BALB/c lymphoma tumors were analyzed with regard to the type of their membrane immunoglobulins (Ig). Using lactoperoxidase iodination of membrane proteins combined with immunoprecipitation and electrophoresis on polyacrylamide gel, three of these cell lines (X16c, L10A and K46) were found to express the monomeric form of IgM and IgD as well as half molecules. One cell line (M12) lacked both IgM and IgD. The apparent mol. wt of the lymphoma micro chain was about 80 000 and exceeded the mol. wt. of 75 000 determined for micro chains secreted by myeloma cells. The mol. wt. of the delta heavy chain was found to be 66 000. Immunofluorescence showed that the L10A and X16c lines expressed lambda light chains on their cell surface. Another Ig-bearing cell line (K46) expressed both lambda and kappa chains. Thus, three out of the four B lymphomas examined expressed both IgM and IgD with light chains of the Lambda type. These results, together with our previous findings which demonstrate the presence of Ia and Fc receptors on the same cells, indicate that spontaneous B lymphomas in BALB/c mice are the malignant counterpart of mature B lymphocytes.

Alkaline phosphatase in adaptation to low dietary phosphate intake

Previous findings suggest that alkaline phosphatase (Alk Pase) may be involved in phosphate transport. Since phosphate reabsorption is enhanced in the kidney and duodenum of animals stabilized on a low-phosphorus diet (LPD), Alk Pase was measured in the kidney, small intestine, and other tissues in LPD rats. In particulate fractions from the renal cortex, intestine, renal medulla, liver, and heart ventricle from LPD rats the activity of Alk Pase was significantly increased but the activities of other plasma membrane enzymes were not different between control and LPD groups. The increased Alk Pase in the renal cortex was localized to the brush border of the proximal tubule histochemically and by measurement of Alk Pase in brush-border preparations. Also in the renal cortex, typical enzymes associated with mitochondria, lysosomes, and cytosol were unchanged with the exception of cytosolic adenosine 3',5' cyclic-monophosphate phosphodiesterase, which was increased in LPD rats. Alk Pase in the renal cortex and intestine may play a role in the enhanced phosphate reabsorption in LPD animals.

Insulin inhibition of hormone-stimulated protein kinase systems of rat renal cortex

Parathyroid hormone (PTH) and glucagon increase the urinary fractional excretion of phosphate, but insulin administration is associated with a decreased fractional excretion of phosphate. It was the purpose of this study to determine whether insulin will antagonize the effects of PTH and glucagon on cAMP levels and protein kinase activation of rat renal cortex. In situ incubation studies were performed on rat renal cortical slices exposed to insulin, PTH, and glucagon. Insulin alone did not affect the tissue cAMP and cGMP levels or the state of protein kinase activation. Preincubation of slices with insulin, however, did significantly inhibit increases in protein kinase activation induced by both PTH and glucagon. Insulin also significantly inhibited PTH-stimulated increases in tissue cAMP levels, but did not blunt the elevations of cAMP levels induced by glucagon. Insulin (10(-9) M) had no effect on either the in vitro activity of adenylate cyclase, basal or PTH-stimulated, or on the activities of low Km cytosolic or membrane-bound cAMP phosphodiesterase. The data show that insulin antagonizes activation of protein kinase by both PTH and glucagon in renal cortex. Separate mechanisms are probably involved for PTH and glucagon interaction. The antiphosphaturic effect of insulin in vivo may result in part from this antagonism at the cellular level.

Effect of hippocampus extirpation in the rat on glutamate levels in target structures of hippocampal efferents

Twenty days after complete uni- or bilateral hippocampus extirpation in rats, a 25% decrease in glutamate concentration was observed in the septum. Glutamate content also decreased in other terminal structures of the hippocampo-subicular system, i.e. entorhinal cortex, nucleus accumbens septi, mammillary bodies and contralateral hippocampus. It is concluded that the fall in glutamate content which is absent in caudate nucleus is specific for target regions of the hippocampal efferents, adding further support to the suggested transmitter role of glutamate in the limbic system.

Mechanism of resistance to the phosphaturic effect of the parathyroid hormone in the hamster

The effect of parathyroid hormone and calcitonin on the renal excretion of phosphate, calcium, and cyclic AMP was evaluated in the thyroparathyroidectomized hamster, a mammal apparently reisstant to the phosphaturic effect of parathyroid hormone. Parathyroid hormone did not increase phosphate excretion, although it decreased excretion of calcium and increased urinary excretion of cyclic AMP. This lack of a phosphaturic response to parathyroid hormone was not reversed by administration of 25-OH vitamin D or infusions of calcium or phosphate. Calcitonin, another potentially phosphaturic hormone, also vailed to increase phosphate excretion but markedly elevated urinary excretion of cyclic AMP. In hamsters pretreated with infusion of urinary ammonium chloride, which decreased plasma and urinary pH, both parathyroid hormone and calcitonin increased excretion of phosphate as well as that of cyclic AMP. Acetazolamide had no phosphaturic effect in ammonium chloride-loaded hamsters, and it decreased cyclic AMP and calcium excretion. Alkalinization of urine by acetazolamide did not prevent the phosphaturic effect of parathyroid hormone in ammonium chloride-loaded hamsters, but it blocked the increase in urinary cyclic AMP excretion. Parathyroid hormone and calcitonin both stimulated adenylate cyclase in a cell-free system (600-g pellet) from hamster renal cortex, elevated tissue cyclic AMP levels, and activated protein kinase in tissue slices from hamster renal cortex. In acid medium, the increase in cyclic AMP and activation of protein kinase in response to parathyroid hormone was diminished, but addition of acetazolamide restored responsiveness of both parameters to control values. Acetazolamide, on the other hand, did not influence adenylate cyclase or its response to parathyroid hormone or cyclic AMP phosphodiesterase activity. We conclude that the lack of a phosphaturic effect of parathyroid hormone and calcitonin in the hamster depends on steps in the cellular action of these hormones, steps that are sensitive to pH subsequent to cyclic AMP generation and protein kinase activation. In addition, acetazolamide may potentiate the phosphaturic effect of parathyroid hormone by promoting accumulation of cyclic AMP in tissue. Thus, the hamster is a particularly useful model for studies of syndromes in which there is renal resistance to phosphaturic hormones.

Influence of hippocampectomy on gastric ulcer in rats

Hippocampectomized male rats were prepared, and the incidence as well as severity of gastric ulceration upon restraint were compared with those of normal control animals and controls with localized damage to the cortex over the hippocampus. In another experiment, observations on gastric ulceration were made without restraint in hippocampectomized animals, normal controls, controls with cortical damage, vagotomized animals and animals that received hippocampectomy as well as vagotomy. Both in restrained and unrestrained states, the incidence of animals with ulcer as well as the number and the total area of ulcers per stomach were significantly larger in the hippocampal animals than they were in the other animal groups. Vagotomy abolished the effect of hippocampectomy upon gastric ulceration in the unrestrained state. We infer that the hippocampus helps to protect the stomach from ulceration partly by controlling vagal activity.

Influence of ginseng on mating behavior of male rats

Experiment on the mating behavior of male albino rats paired with receptive females established that in comparison with control animals, males under the influence of ginseng (a) began ejaculation earlier and repeated the action more often in a 45-minute observation period and (b) deposited more copulation plugs in 10 days. The data suggest that ginseng facilitates the mating behavior of male rats.

Effect of hippocampectomy on sleep patterns in cats

The study was planned to see if the hippocampus has an influence on fast wave sleep (FWS) as well as on slow wave sleep (SWS). From 8 male cats EEG, EMG and EOG were recorded for 24 h, first under normal conditions, secondly after cortical damage to the dorsal marginal portion of posterior ectosylvian gyrus, and thirdly following hippocampectomy done through the cortical damage. From the records, SWS, FWS and the sleep state (defined as a sequence of SWS or SWS-FWS phases between two successive waking states) were measured in terms of their occurrence, the mean duration and the total time they occupied in the day, night and 24 h. In addition, sleep sequences were classified according to the number of constituent sleep phases. Cortical damage did not affect SWS, FWS, or sleep state with regard to their occurrence, the mean duration, and the total time they occupied in 24 h. Nor did it affect the proportion of short and long sequences. The circadian variation of sleep was clearly retained. Hippocampectomy significantly reduced the total time occupied by sleep state, SWS and FWS, increased the occurrence of sleep state and SWS phase against decreased incidence of FWS phase, and reduced the mean duration of sleep state and SWS phase. Hippocampectomy also significantly increased the occurrence of sleep sequences with only one SWS phase at the cost of sequences with alternating SWS and FWS phases. Following hippocampectomy, the circadian variation of sleep was not only retained, but actually exagerated. The hippocampus in inferred to facilitate the FWS as well as the SWS phase of sleep.

The sodium and potassium concentrations in the uterine fluid of the rat at the time of implantation

Rat uterine fluid Na+ and K+ concentrations were calculated from the ratio of the Na+ and K+ concentrations in uterine washings, on the assumption that the sum of Na+ and K+ (mequiv./l) is the same in blood serum and in uterine fluid. Uterine fluid volumes were likewise calculated from the total quantity of Na+ and K+ washed out of the uterine horn.

The mean uterine fluid volume was 7·6 μl per horn and the mean potassium concentration was 45·8 mequiv./l on day 6 of normal pregnancy. Both oophorectomy alone on day 2 and oophorectomy followed by daily injections of progesterone, cause a marked reduction of the uterine fluid volume on day 6 of pregnancy. Oophorectomy on day 2 caused a significant reduction in the uterine fluid K+ concentration. Administration of high and low doses of progesterone after oophorectomy on day 2 of pregnancy resulted in uterine fluid potassium concentrations higher and lower, respectively, than the normal day 6 fluid.

It is postulated that a high uterine fluid K+ concentration is essential for blastocyst-endometrial contact preceding implantation and that this may be significant with regard to certain types of delayed implantation.