Gram Of Wet Tissue Research Articles

Quantitation and isomeric structure analysis of free oligosaccharides present in the cytosol fraction of mouse liver: detection of a free disialobiantennary oligosaccharide and glucosylated oligomannosides.

The amounts and isomeric structures of free oligosaccharides derived from N-linked sugar chains present in the cytosol fraction of perfused mouse liver were analyzed by tagging the reducing end with 2-aminopyridine followed by 2-dimensional HPLC mapping with standard sugar chains. Sixteen pyridylaminated (PA-) oligomannosides terminating with a PA-GlcNAc residue (GN1-type), three glucose-containing oligomannosides, and four oligomannosides terminating with a PA-di-N-acetylchitobiose (GN2-type) were detected. The total contents of the GN1- and GN2-type oligomannosides were 3. 4 and 0.5 nmol, respectively, per gram of wet tissue. Maltooligosaccharides (dimer to pentamer) were also detected, the total content of which was 13 nmol per gram of wet tissue. Besides these oligosaccharides, a PA-disialobiantennary sugar chain-the sole complex-type sugar chain-was also detected. All the oligomannosides identified had partial structures of Glc(3)Man(9)GlNAc(2)-p-p-dolichol, revealing that they were metabolic degradation products. Manalpha1-2Manalpha1-2Manalpha1-3(Manalpha1-6)++ +Manbeta1-4GlcNAc (M5B') was the major oligomannoside, suggesting that cytosolic endo-beta-N-acetylglucosaminidase and neutral alpha-mannosidase participate in the degradation, because these enzymes have suitable substrate specificities for the production of M5B'. Degradation by these enzymes seems to be the main pathway by which oligomannosides are degraded in mouse cytosol; however, small amounts of Manalpha1-6(Manalpha1-3)Manalpha1-6(Manalpha1-3) Manbeta1-4(GlcNAc)1-2 and related oligomannosides together with parts of their structures were also detected, suggesting that there is another minor route by which cytosolic free oligomannosides are produced.

Embryonic Delivered Dose of Isotretinoin (13-cis-Retinoic Acid) and Its Metabolites in Hamsters

All-trans-retinoic acid (all-trans-RA) is required in normal embryogenesis and both deficiency and excess are teratogenic. Isotretinoin (13-cis-RA) is teratogenic in all species examined; based on administered dose, humans appear most sensitive, followed by (in order or decreasing sensitivity) monkey, rabbit, hamster, mouse, and rat. Identification of the teratogenic threshold in these species is difficult because RAs are normal physiologic constituents. The rabbit no-observed-adverse-effect-level (NOAEL) and lowest-observed-adverse-effect-level (LOAEL) administered doses (3 and 15 mg/kg/day, respectively, on gestation Days 8–11) are less than the corresponding values in hamster (7.5 and 37.5 mg/kg/day, respectively, on gestation Days 7 and 8), but drawing conclusions from administered dose alone ignores differences in absorbed, metabolized, and embryonic delivered dose. Therefore, distribution and metabolism studies of 13-cis-RA at the NOAEL and LOAEL in pregnant hamsters were performed and plasma and tissue concentrations of parent compound and metabolites were compared to those found in rabbits. Metabolites of 13-cis-RA common to all species include three RAs (all-trans-RA, all-trans-4-oxoRA, 13-cis-4-oxoRA) and the glucuronide conjugate of 13-cis-RA (13-cis-RAG). As in rabbits, we found 13-cis-4-oxoRA also to be the major metabolite of 13-cis-RA in hamster plasma, peripheral tissues, and embryo. Of maternal tissues, peak 13-cis-RA concentrations were highest in liver. Total concentration of RA (13-cis-RA + 13-cis-4-oxoRA + all-trans-RA + all-trans-4-oxoRA) per gram of wet tissue was greatest in maternal liver, followed by that in lung, adipose tissue, muscle, kidney, and brain. At the NOAEL, total RA plasmaCmaxin hamster was 6 times that in rabbit; at the LOAEL, hamster plasma total RACmaxwas 4 times that in rabbit. Hamster absorbed and metabolized dose (as AUC of plasma total RA) at the NOAEL and LOAEL was 2.6 and 2.4 times that in rabbit, respectively. In the embryo, hamster total RACmaxwas 2.7 times (at NOAEL) and 2.6 times (at LOAEL) that in rabbit. However, embryonic delivered dose (total RA AUC in hamster and rabbit embryo, respectively) at the NOAEL (2.08 and 2.14 μg·hr·g−1) and LOAEL (5.34 and 5.54 μg·hr·g−1) was virtually identical. Embryonic AUCs in hamster and rabbit for all-trans-RA and all-trans-4-oxoRA, metabolites which transactivate directly the nuclear RA receptors (RARs), were also very similar at the NOAEL (0.66 and 0.81 μg·hr g−1) and at the LOAEL (1.14 and 1.32 μg·hr g−1). Based on embryonic delivered dose, we suggest that 13-cis-RA is an equipotent teratogen in hamster and rabbit.

Glycosaminoglycan concentration in synovium and other tissues of rabbit knee in relation to synovial hydraulic resistance.

1. The hydraulic resistance of the synovial lining of a joint, a key coupling coefficient in synovial fluid turnover, is thought to depend on the concentration of biopolymers (glycosaminoglycans (GAGs) and collagen) in the synovial intercellular spaces, because these polymers create hydraulic drag. The primary aim of this study was to obtain microscopically separated, milligram samples of the very thin synovium from eight rabbit knees, and to analyse these quantitatively for GAGs (chondroitin sulphate, heparan sulphate and hyaluronan) and collagen to allow comparison with published hydraulic resistance data. Synovial fluid and femoral cartilage were also studied. 2. Synovium comprised 73 +/- 3% water by weight (mean +/- S.E.M.). Of the 270 mg solid per gram of wet tissue, protein formed 136 mg (by automated amino acid analysis), and of this 94 mg was collagen by hydroxyproline analysis. From the collagen mass and fibril volume fraction (0.153 of tissue by morphometry), fibrillar specific volume was calculated to be 1.43 ml per gram of molecular collagen, and fibril water content 47% by volume. 3. The concentration of chondroitin 4-sulphate (C4S) plus chondroitin 6-sulphate (C6S), measured by capillary zone electrophoresis was 0.55 mg per gram of synovium--much greater than in synovial fluid (0.04 mg g-1) and much less than in cartilage (27.8 mg g-1). The C4S/C6S ratio in synovium (7.3) differed from that in cartilage (0.7), indicating that different proteoglycans predominated in synovium. The heparan sulphate concentration, assayed by radioactive Ruthenium Red binding, was 0.92 mg per gram of synovium (synovial fluid, 0.08 mg g-1; cartilage, 0.72 mg g-1). 4. In contrast to sulphated GAGs, the hyaluronan concentration was highest in synovial fluid (3.53 mg g-1; biotinylated G1 domain binding assay). The concentration in synovial interstitium was only 0.56 mg g-1 (corrected for interstitial volume fraction, 0.66), even though there is open contact between synovial interstitium and synovial fluid. This may be due to exclusion or washout. 5. Total GAG mass was approximately 4 mg per gram of synovial interstitium. A model of trans-synovial flow indicated that a uniform GAG concentration of 4 mg g-1 is less than 1/3rd of that required to explain the experimental estimate of synovial hydraulic resistance. Errors in the resistance estimate do not appear to be large enough to resolve the problem. It is possible, therefore, that additional polymeric material in the interstitium, such as glycoproteins and proteoglycan core protein, may contribute to the hydraulic resistance.

Secretion of unconjugated estrone during pregnancy and around parturition in goats

The secretion of unconjugated estrone and its production site in pregnant goats were investigated in vivo. The mean estrone concentration (n = 15) in the peripheral plasma increased gradually, being 83 pg/ml on Day 40 and 483 pg/ml on Day 140 after mating. The estrone concentration increased rapidly after Day 2 before partum, reaching a peak at parturition (2370 pg/ml), and falling to 171 pg/ml at Day 1 post partum. The concentrations of estrone from the umbilical vein and umbilical artery did not differ from that found in the maternal jugular vein, suggesting that the fetus does not take part in estrogen production. The estrone concentration from the uterine vein after the fetus was removed was higher than the concentrations found in the maternal jugular vein and umbilical artery. In the placental tissue, a high concentration of estrone (18157 pg per gram of wet tissue) was detected. These findings suggest that the main production site of unconjugated estrone is the placenta.

Speciation and genotoxicity of butyltin compounds

The northern part of the Elbe river in Germany is one of the most highly polluted rivers in Europe, in particular with toxic organotin compounds. Two major anthropogenic sources are the Hamburg harbour area with intensive docking activities and a chemical plant in Bitterfeld close to the Mulde river in eastern Germany. Tributyltin is leached from the antifouling paints and enters the water phase. Thus, the Hamburg harbour area is highly contaminated with tributyltin and its degradation products, di- and mono-butyltin. Untreated run-off waters of an organotin plant in Bitterfeld contaminate the Mulde, a tributary of the Elbe, extensively. The Mulde sediments contain butyltin compounds of the order of mg of Sn per kilogram of dry mass. In Raguhun sediments, concentrations of tetrabutyltin and tributyltin were 1.8 ± 0.4 mg of Sn per kilogram of dry mass and 1.1 ± 0.2 mg of Sn per kilogram of dry mass, respectively. Remobilization of the sediments during high water periods transports the contaminants along the Mulde river into the Elbe river. Tetrabutyltin can be detected in the Elbe river as far as Cuxhaven and its estuary. To evaluate the ecological impact, fish tissues were analysed for their butyltin content and the data were correlated with the butyltin content in the surrounding water. The analysis of different fish tissues: liver, kidney, gills and the edible tissue, shows a clear enrichment of the tributyltin species. In the liver, tributyltin concentrations of up to 200 ng of Sn per gram of wet tissue were found. Bioconcentration factors were calculated to be of the order of 4500–9000. Tetrabutyltin could not be found in all the tissues, whereas it is present in water. The low bioavailability of tetrabutyltin is presumably caused by the low amount of tetrabutyltin in the dissolved constituents of water. Up to 99% of the tetrabutyltin content in water is bonded to particulate matter. The butyl groups influence the toxic behaviour of the butyltins. Although the toxic effects of butyltins on different organisms are well investigated, the genotoxic potential of the butyltins has received much less attention. The SOS-Chromotest was used to evaluate their genotoxicity. All the butyltins were found to be genotoxic; dibutyltin was the most genotoxic (10–40 µg of Sn per litre) followed by tri-, tetra- and mono-butyltin. An enhancement of the genotoxicity of all butyltins was observed using spiked lake water instead of distilled water. For the analysis of the butyltin compounds sodium tetraethylborate was used as in situ ethylating agent in the buffered samples. No pre-extraction steps with complexing agents are necessary. The extraction yields of all butyltin compounds are in the range of 82–94% for water; 76–88% for suspended particulate matter, sediment and soil; 80–94% for organisms; and 76–97% for air samples. The limit of detection of GC–AAS is 25 ± 5 pg of Sn per microlitre injected volume (3σ of the baseline noise).

The dermatan sulfate proteoglycans of the adult human meniscus

The dermatan sulfate proteoglycans decorin and biglycan were extracted from pooled adult human menisci with 4 M guanidinium chloride and purified by successive cesium chloride density gradient centrifugation, ion exchange chromatography, and gel filtration. A final yield of about 2 mg of dermatan sulfate proteoglycan per gram of wet tissue was obtained. The proteoglycan is predominantly decorin with some biglycan, and the dermatan sulfate chains contain about 70% of their uronic acid residues as iduronate and possess about three times as much 4-sulfation as 6-sulfation of their N-acetylgalactosamine residues. On gel filtration under associative conditions, about half of the proteoglycan exhibits self-association. This includes most of the biglycan but also a substantial proportion of decorin. The molecules that show self-association appear to have longer dermatan sulfate chains, though there is no apparent difference in their overall composition. The predominance of decorin in the adult meniscus and its ability to interact both with itself and collagen fibrils is compatible with a role in maintaining tissue integrity and strength.

Posthatching Changes in the Immunoglobulin A Concentration in the Jejunum and Bile of Turkeys

An experiment was conducted to document the age-related changes in IgA concentration in the small intestine of newly hatched turkey poults reared in floor pens and to determine whether infection with stunting syndrome (SS) affects age-related changes. Day-old turkey poults were dosed per os with .5 mL of saline carrier (control) or with .5 mL of one of two dilutions (250- or 2.5 × 106-fold) of a “crude” SS-causing inoculum. Inoculation with the 250-fold dilution depressed body weight gain (P<.01) throughout the experiment and impaired feed efficiency (P<.05) at 5 and 9 days of age as compared with the control group. After 9 days of age, all inoculated poults utilized feed more efficiently than did control poults (P<.01). Stunting syndrome did not affect IgA concentrations in either bile or jejunum at any specific age. Age-related changes in IgA concentrations, however, were observed. Bile IgA decreased from 1 to 9 days of age, and then increased until 29 days of age. The IgA concentration in jejunal tissue increased linearly from 1 to 29 days of age (P<.01), whether expressed as IgA concentration per gram of wet tissue or as percentage of total protein in jejunum. Age-related changes in IgA concentration in both bile and jejunum suggest that the secretory immune system associated with the digestive mucosa is not fully developed at the time of hatch.

Chronic Verapamil Treatment Depresses Automaticity and Contractility in Isolated Cardiac Tissues

Chronically administered verapamil can accumulate in cardiac tissues and may depress cardiac function despite low plasma concentration. To examine this, two groups of rabbits were injected intraperitoneally twice a day with either 1 mg/kg verapamil or saline for 28 days. Fourteen hours after the last dose, right atrial tissue and right ventricular papillary muscle were isolated. Plasma and myocardial tissue concentrations of verapamil were determined. Plasma samples contained no detectable amounts of verapamil, but the myocardium contained 2.1 +/- 0.6 (mean +/- SE) ng of verapamil per gram of wet tissue. Spontaneous action potentials recorded from the sinoatrial node in the verapamil-treated group showed decreases in the phase 0 and phase 4 depolarization rates, a slower pacemaker rate, and an attenuated response to epinephrine compared with the saline-treated group. Papillary muscle in the verapamil-treated group exhibited a significantly lower force of contraction and a depressed contractile response to epinephrine compared with the control group. There were no differences in rate or contractile responses the day after single injection with 2 mg/kg verapamil or saline twice a day. Myocardial verapamil concentration increased with the duration of treatment and with the doses given; myocardial verapamil concentration was 3.0 +/- 0.6 ng/g wet tissue in the group treated for 28 days with 2 mg/kg verapamil. Our study shows that chronic treatment of rabbits with verapamil decreases cardiac chronotropic and inotropic responses to adrenergic stimuli despite no detectable verapamil in plasma, and that accumulation of verapamil in the myocardium is probably associated with these effects.

Biochemical Profiles in Cows with Abomasal Displacement Estimated by Blood and Liver Parameters*

The metabolic status of normal lactating cows and of cows suffering from abomasal dilatation was evaluated by examination of blood parameters and by determination of the fat and glycogen content in liver biopsies. The method for examination of the liver biopsies is described. In clinically normal lactating cows the liver contains less than 20 mg triglycerides (TG) and more than 20 mg glycogen per gram of wet tissue. Cows suffering from abomasal displacement all showed hyperglycemia and in most of them a fatty to very fatty liver was found. The degree of hyperglycemia depends on the amount of liver glycogen and is independent of the liver TG content. The degree of ketonemia also depends on the liver glycogen content.

Cell cultures enriched in oligodendrocytes from the central nervous system of trout in terms of phenotypic expression exhibit parallels with cultured rat schwann cells

Oligodendrocytes were isolated from the white matter of young trout by Percoll density centrifugation of enzymatically dissociated tissue and cultured on poly-D-lysine-coated petri dishes. Using antisera recognizing myelin-specific compounds of fish CNS (36K, IP2) up to 72% of the isolated cells could be identified as oligodendrocytes with an average yield of 4 x 10(6) cells per gram of wet tissue. Taken in culture, the cells rapidly regenerated their processes and soon acquired a morphology closely resembling mammalian oligodendrocytes in vitro. On the other hand, in terms of phenotypic expression, interesting parallels were revealed with the known in vitro behavior of Schwann cells: Galactocerebroside, which in mammalian oligodendrocytes is persistently expressed over longer periods of time in vitro, rapidly disappeared from the surface of cultured trout oligodendrocytes. In contrast, the fish CNS myelin glycoprotein IP2, which like IP1 is immunologically related to the major myelin product of Schwann cells, P0, was continuously expressed over several weeks in culture. Two other myelin protein constituents, 36K and IP1, transiently declined in vitro, but later on fully reappeared in the glial cells of trout. The present cell culture system offers an experimental model for studying in vitro the factors underlying oligodendroglial regeneration and remyelination in the fish CNS.

Biochemical pharmacology of 5,6-dihydro-5-azacytidine (DHAC) and DNA hypomethylation in tumor (L1210)-bearing mice

Dihydro-5-azacytidine (DHAC) is a hydrolytically stable congener of 5-azacytidine, which retains antileukemic activity against experimental leukemias. The biochemical pharmacology of DHAC was studied in tumor-bearing mice in order to elucidate the mode of action of this drug. We found that after an LD10 dose of DHAC, the plasma peak concentration achieved was 317 microM and was eliminated biexponentially, with a t1/2 alpha of 1.03 h and a t1/2 beta of 5 h. By 4 h, an unidentified metabolite of [3H]DHAC peaked and was eliminated biexponentially, with a t1/2 alpha of 1.06 h and a t1/2 beta of 10.6 h. [3H]DHACTP was the major anabolite in the L1210/0 cells, and was also eliminated biexponentially, with a t1/2 alpha of 4.3 h and a t1/2 beta of 12.2 h. An unknown anabolite of [3H]DHAC that eluted 5 min after [3H]DHACTP, between UTP and ATP, peaked at 3 h and could possibly be the deoxy-derivative [3H]DHAdCTP. A tissue distribution study revealed that the liver, L1210/0, and lung accumulate the most radioactivity per gram of wet tissue. Methylation studies showed that an LD10 dose of [3H]DHAC resulted in a 25.06% hypomethylation of DNA in L1210/0 cells and a 46.32% hypomethylation in a deoxycytidine kinase mutant cell line L1210/dCK(-), compared with their respective controls.

Epidermal growth factor in the mouse kidney: developmental changes and intranephron localizations.

The developmental changes in epidermal growth factor (EGF) have been studied in tissue homogenates, kidney slices, and microdissected nephron segments of the mouse. Immunoreactive EGF concentration per milligram of protein increased in the kidney by about 20-fold from 1 week to 3 weeks of life, reaching the highest levels between 5 and 7 weeks, and decreasing by 10 weeks of life. The time course of the changes was different from those of submaxillary and urinary EGF. Above 7 weeks of age, kidney EGF was higher in female than in male mice. Among various zones of the kidney (outer cortex, inner cortex, outer medulla I, II and papilla), the outer medulla I and II contained the highest quantities of EGF per gram of wet tissue. The highest EGF content per millimeter length was observed in the medullary and cortical thick ascending limbs of Henle's loop. The amounts exceeded by about 4.5-fold those found in glomeruli and in proximal convoluted and proximal straight tubules, and by about 3-fold those present in distal and collecting tubules. Unilateral nephrectomy resulted in no significant changes in EGF levels in the contralateral kidney. The results suggest that the ontogeny of kidney EGF is different from that of the EGF found in the submaxillary gland, and that there is nephron heterogeneity in EGF content.

A quantitative study on the distribution of asbestos bodies in extrapulmonary organs.

We made a quantitative study of the distribution of asbestos bodies (ABs) in 13 extrapulmonary organs. We selected 26 male subjects and subdivided them into three groups: Group I had 10(2) to less than 10(3) ABs per gram of wet tissue in their lungs; group II had 10 to 99 ABs; and group III had no ABs. In group I, one or more ABs were identified in at least 6 (53.8%) of the examined extrapulmonary organs. In group II, 23.7% of the examined organs had one or more ABs. In group III, no ABs were found. These results seem to indicate that with modest exposure in the lung, the other organs are often exposed to asbestos with some degree. Moreover, the number of AB in the esophagus was significantly larger than that in 9 of the other 12 organs in group I. The pancreas and the spleen were also supposed to be more preferential sites of exposure. However, the relationship between exposure and its effects in extrapulmonary organs remains to be elucidated.

Effects of Neonatal Undernutrition and Subsequent Nutritional Rehabilitation or Administration of Thyroxine and Hydrocortisone on the Inositol Phosphatase Activities in Rat Intestine

Undernutrition during the suckling period imposed by maternal protein deficiency during lactation resulted in elevated inositol triphosphatase activity (units per gram of wet tissue) in the ileum and lower phytase activity in the duodenum and jejunum. Activities of inositol triphosphatase in the duodenum and jejunum and phytase in ileum were unaffected. Postweaning nutritional rehabilitation resulted in elevated specific activities of both enzymes in all segments; however, activities of whole segments were similar to the corresponding control values. Elevation of inositol triphosphatase (ileum) and decline of phytase (duodenum and jejunum) activities due to undernutrition were reversed by the administration of hydrocortisone or thyroxine during undernutrition. These results suggest that maturation of activities of inositol triphosphatase in ileum (by hydrocortisone) and phytase in all segments (by both hydrocortisone and thyroxine) is under hormonal regulation, and the effects of neonatal undernutrition may be partly due to hormonal imbalances.

Effects of Neonatal Undernutrition and Subsequent Nutritional Rehabilitation or Administration of Thyroxine and Hydrocortisone on the Inositol Phosphatase Activities in Rat Intestine

SummaryUndernutrition during the suckling period imposed by maternal protein deficiency during lactation resulted in elevated inositol triphosphatase activity (units per gram of wet tissue) in the ileum and lower phytase activity in the duodenum and jejunum. Activities of inositol triphosphatase in the duodenum and jejunum and phytase in ileum were unaffected. Postweaning nutritional rehabilitation resulted in elevated specific activities of both enzymes in all segments; however, activities of whole segments were similar to the corresponding control values. Elevation of inositol triphosphatase (ileum) and decline of phytase (duodenum and jejunum) activities due to undernutrition were reversed by the administration of hydrocortisone or thyroxine during undernutrition. These results suggest that maturation of activities of inositol triphosphatase in ileum (by hydrocortisone) and phytase in all segments (by both hydrocortisone and thyroxine) is under hormonal regulation, and the effects of neonatal undernutrition may be partly due to hormonal imbalances.

2-Methylfuran toxicity in rats—Role of metabolic activation in vivo

Administration of a single ip dose of 2-methylfuran (2-MF) to male Sprague-Dawley rats at a dose of 100 mg/kg produced centrilobular necrosis of the liver and bronchial injury of the lung, the severity of the lesions increasing with increasing doses up to 400 mg/kg. Kidneys, however, showed no visible evidence of tissue damage even at the highest dose. Liver injury was also evidenced by an increase in serum glutamic pyruvic transaminase (SGPT) levels. Tissue distribution and covalent binding studies conducted over a dose of 50–200 mg/kg of [ 14C]2-MF indicated that the total radioactivity present per gram of wet tissue was in the order of liver > kidney > lung > blood. Covalent binding of the label to protein was greatest in the liver followed by kidney and the lung. Radioactivity bound covalently per milligram of DNA was also highest in the liver followed by kidney. Tissue distribution and covalent binding studies were conducted over a period of 0.5 to 24 hr after an ip dose of 100 mg/kg of [ 14C]2-MF. Maximal covalent binding was observed in the liver at 4 hr. At all time points binding of the label was greatest in liver, followed by kidney. Liver glutathione levels were depressed following 2-MF administration. Pretreatment of rats with phenobarbital markedly increased the covalent binding to protein and DNA and caused a twofold increase in SGPT compared to rats treated with 2-MF alone. Pretreatment with 3-methylcholanthrene had no effect on either parameter. Administration of N-octylimidazole, an inhibitor of cytochrome P-450, prior to administration of the radiolabeled 2-MF decreased the covalent binding of the label to protein and DNA. Moreover, the SGPT levels remained the same in the pretreated rats compared to the rats treated with vehicle alone. Thus, pretreatment with phenobarbital, an inducer of cytochrome P-450, enhanced both covalent binding and toxicity while prior treatment with N-octylimidazole, an inhibitor of cytochrome P-450 decreased covalent binding and prevented hepatotoxicity of 2-MF. These results support the view that at least some of the toxic effects of 2-MF are mediated by reactive metabolite(s) formed in vivo.

The role of high-energy phosphate in norepinephrine-induced acute renal failure in the dog.

Previous studies have demonstrated that pretreatment with mannitol, furosemide, or bradykinin can attenuate the severity of norepinephrine-induced renal functional impairment. The present studies were designed to evaluate the possibility that these agents are protective, in part, by preserving cellular metabolic integrity. The renal cortex was repetitively biopsied during the course of this study, and high-pressure liquid chromatography was used to analyze the tissue content of adenine nucleotides (expressed in nanomoles per gram of wet tissue). The adenine nucleotide charge ratio (CR) and total adenine nucleotide (TAN) content were calculated as indices of cellular metabolic integrity. In addition to the above-established protective agents, phenoxybenzamine was used to evaluate a direct toxic effect of norepinephrine on renal tissue. Inulin clearance at 3 hours post infusion (expressed as a percent of control) was 7% with norepinephrine alone and, in the protected groups, 36% with bradykinin, 61% with furosemide, 51% with mannitol, and 100% with phenoxybenzamine. There was no change in CR or TAN with phenoxybenzamine. In contrast, during norepinephrine administration CR fell significantly in all other groups. Three hours after stopping norepinephrine, CR had returned toward control values and the level of CR was significantly better in all protected groups when compared with norepinephrine alone. Similarly, the levels of TAN were significantly diminished in the norepinephrine-alone group when compared to all protected groups, and there was significantly more tubular necrosis as well. The maintenance of higher levels of TAN and the preserved ability to regenerate adenosine triphosphate in the protected groups, when compared to the norepinephrine-alone group, support the contention that these agents offer protection, at least in part, by preserving cellular metabolic integrity.

Histamine and Human Heart

Heart fragments obtained from human right atrium contain 1.5 +/- 0.2 micrograms of histamine per gram of wet tissue. Human heart spontaneously synthesizes significant amounts of PGI2, PGF2 alpha, PGE2 and TxA2. The Ca2+ ionophore A 23187 (0.5-3 micrograms/ml) dose-dependently induces histamine release and prostanoid production. Histamine (0.5-1 micrograms/kg/min) infusion in 10 normal donors produced an increase in heart rate and a significant depression of the ST segment. Selective H1 receptor stimulation in patients undergoing cardiac catheterization resulted in a decrease of the mean aortic pressure and of coronary vascular resistance.

Microvascular heparin-like species with anticoagulant activity.

Calf microvasculature was isolated from retina and cerebral gray matter. These preparations contained 0.048-0.060 U of heparin-like anticoagulant activity per gram of wet tissue. The retinal microvascular material contained no detectable mast cells. The anticoagulant potency of this product was associated solely with endothelial cells. This property appears to be due to a heparinlike proteoglycan since molecular species with biologic activity are precipitated with 10% (wt/vol) trichloroacetic acid and are destroyed by incubation with Flavobacterium heparinase. Furthermore, the above component functions in a manner virtually identical to heparin since approximately 60% of these species with anticoagulant activity bind to antithrombin-concanavalin A-Sepharose 4B, and only 15% of their biologic potency is expressed in the presence of antithrombin modified near the mucopolysaccharide binding domain. The cerebral microvascular tissue contained a trace subpopulation of mast cells (approximately 0.3%). The anticoagulant activity of this preparation is most probably associated with both endothelial cells and mast cells. However, complete separation of these two cellular elements has proven difficult with current methodology.

Seasonal changes in testicular gonadotropin receptors and steroid content in the ram.

To determine if seasonal changes in plasma gonadotropin levels and testicular weight are accompanied by changes in the number of testicular gonadotropin receptors, testicular LH and FSH receptor numbers were measured every 3 months in the testes of 2-yr-old rams during 2 successive yr. The intratesticular contents of testosterone and 17β-estradiol were also measured. The binding affinity of testicular receptors for LH (1.9 ± 0.2 1010 M-1) and FSH (4.1 ± 0.2 109 M-1) did not vary with season. When expressed per milligram of membrane proteins or per gram of wet tissue, the concentrations of LH and FSH receptors were maximum in June. When expressed per testis, however, the number of LH receptors increased linearly from December to September (from approximately 2 to 5 pmol/ testis), then decreased rapidly from September to December. The number of FSH receptors per testis was minimum between December and March (∼4 pmol/testis), increased by J ne, was maximum between June and September (∼12 pmol/testis), and th...