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Biomedical subjects

B Uvnäs

Publications and source records attributed to B Uvnäs.

At least 19 recordsLinked to original sources
PubMed1979

Effect of splenic nerve stimulation on the contents of noradrenaline, ATP and sulphomucopolysaccharides in noradrenergic vesicle fractions from the cat spleen.

In order to assess the effect of splenic nerve stimulation on the contents of noradrenaline, ATP and 35S-labelled compounds in noradrenergic vesicles from the spleen, experiments were carried out on the cat spleen in situ, its frontal portion being used as control. Particulate fractions containing noradrenergic vesicles were isolated on Ficoll gradient centrifugation of homogenates from both portions of the spleen. The cats received phenoxybenzamine (10 mg/kg) and imipramine (5 mg/kg) to inhibit the contractive response of the spleen to nerve stimulation and the reuptake of noradrenaline (NA) into nerve terminals. Administration of the drugs did not significantly affect the levels of NA, ATP and 35S (presumably in sulphomucopolysaccarides, SMPSs). In response to prolonged stimulation of the splenic nerve a significant loss of NA from noradrenergic vesicles occurred, whereas levels of ATP and 35S-labelled compounds remained unchanged. The results indicate that a discharge of NA in response to nerve stimulation is not accompanied by simultaneous discharge of ATP and SMPSs.

Adenosine Triphosphate↗
PubMed1979

The effect of surgical sympathectomy and of neonatal treatment with 6-hydroxydopamine and guanethidine on particle-bound noradrenaline and 35S-sulphomucopolysaccharides.

Five to six weeks after bilateral stellate ganglionectomy, noradrenaline (NA) levels in cats' atria were reduced to approximately 20% of controls. In vivo uptake of 3H-NA and of 35S-sulphate into gradient fractions containing noradrenergic vesicles from the atria decreased to approximately 30% and approximately 40%, respectively. The uptakes of 3H-NA and 35S-sulphate were significantly correlated in both control and ganglionectomized cats, and the distributions of 3H and 35S on the gradients were parallel. The findings suggest that sulphomucopolysaccharides (SMPSs) may be localized in noradrenergic vesicles, possibly participating in the storage of Na. in 10-week-old rats treated neonatally with either 6-hydroxydopamine (6-OH-DA) or guanethidine, levels of NA in the heart, spleen and salivary glands were decreased to less than 10% and to 10-20%, respectively; in the seminal ducts to 33% and 45%, respectively. 3H-NA uptake into noradrenergic-vesicle-enriched subcellular fractions from the heart, spleen and salivary glands of 6-OH-DA treated rats decreased almost to the extent of NA depletion but in the seminal ducts the decrease was less marked. Guanethidine treatment left the uptake unaffected, except for the spleen. The discrepancy between storage and uptake suggests that surviving neurons display during their outgrowth into tissues a high uptake capacity but lack full NA synthesis. 35S-sulphate incorporation into non-lipid compounds, presumably SMPSs, in the noradrenergic-vesicle-enriched fractions appeared unaffected or increased over corresponding control levels, possibly due to high synthetic activity in the growing neurons.

Adrenal Glands↗
PubMed1979

Release of gastrin from the skeletal muscles and from the antral mucosa in cats induced by sulfonuric drugs.

The present observations indicate that sulfonuric drugs release gastrin both from peripheral nerves in striated muscles and from endocrine-like cells in the gastrointestinal tract. Gastrin appears in perfusates of extirpated cat legs after administration of tolbutamide or glibenclamide (5-50 mg/kg or 5-500 microgram/kg perfused tissue respectively) to the perfusion medium. Furthermore gastrin is released into the portal vein of cats after i.v. administration of glibenclamide (5-50 microgram/kg). The finding that sulfonuric drugs not only release insulin from beta-cells in the pancreas, but also gastrin from gastrin producing cells in the stomach as well as from nerve fibers in the skeletal muscles, indicate that sulfonuric drugs have more wide spread effects than previously assumed. Possible consequences of the drug induced release of peptides from peripheral nerves as well as of the release of gastrin from the gastrointestinal tract are discussed.

Animals↗
PubMed1979

Effect of sensitization on spontaneous and phosphatidylserine-induced histamine release and on cyclic AMP and GMP levels in isolated rat mast cells.

Sprague Dawley rats were sensitized with 20 microgram or 100 mg egg albumin (using pertussis vaccine as adjuvant). Mast cells isolated from the former group of animals showed a higher degree of histamine release upon challenge in vitro with egg albumin than those from the latter group. Using the lower amount of antigen for immunization mast cells from Hooded Lister rats showed an even higher degree of histamine release induced by antigen. An increased antigen-induced histamine release was associated with an increased spontaneous and phosphatidylserine-induced histamine release. Histamine release induced by phosphatidylserine was found to be specific in so far as it was calcium dependent and theophylline-inhibited. The basal level of cyclic AMP in mast cells was significantly depressed by sensitization. There was a relationship between the cyclic AMP/cyclic GMP ratio and the degree of spontaneous, phosphatidylserine-induced and anaphylactic histamine release. The results suggest that sensitization induces an increased release of histamine not only to the specific antigenic stimulus but also to more unspecific stimuli. Concomitantly there is a fall in the cyclic AMP/cyclic GMP ratio. The relationship between these two phenomena is discussed.

Anaphylaxis↗
PubMed1977

Heptadecapeptide gastrin in the vagal nerve.

Immunoreactive gastrin was present in vagal nerves from cats, dogs, and human beings. The abdominal portion of the vagus contained gastrin in amounts ranging from 16 to 273 pmol/g of nerve tissue (wet weight). The thoracic and cervical portion of the vagi contained only minute amounts of gastrin. Gel chromatography of extracts of human, canine, and feline abdominal vagi monitored by region-specific antisera against heptadecapeptide gastrin and triacontatriapeptide cholecystokinin revealed that the vagal gastrin immunoreactivity predominantly consisted of heptadecapeptide gastrin. In addition, the vagi contained small amounts of the NH2-terminal tridecapeptide gastrin fragment as well as of the putative biosynthetic gastrin precursors, components I and II. No cholecystokinin-like molecules were demonstrable. Immunocytochemical studies demonstrated gastrin-containing nerves in the intestinal wall. The nerves were found to be most numerous in the large and distal small intestine. These findings suggest that heptadecapeptide gastrin may represent a new vagal neurotransmitter.

Animals↗
PubMed1977

On the cation exchanger properties of rat mast cell granules and their storage of histamine.

Mast cell granules free of a surrounding membrane were isolated from water-lysed rat peritoneal and thoracic mast cells by differential centrifugation. The granules were depleted of their histamine by suspension in 10 mM sodium phosphate buffer and the sodium-charged granules then converted into the "hydrogen form" by repeated washing in slightly acid deionized water. The cation exchanger properties of the mast cell granules were investigated by testing the applicability of the Rothmund-Kornfeld equation for cation exchangers to the binding of Na+ and Hi+ ions to granule sites. The results lend further support to the view that the mast cell granule acts as a cation exchanger with the exchanger function localized to protein carboxyls in the protein-heparin complex of the granule matrix.

Animals↗
PubMed1977

The ability of ATP-free granule material from bovine adrenal medulla to bind inorganic cations and biogenic amines.

Bovine adrenal medullary granules isolated by millipore filtration were depleted of CA and ATP by dialysis. The resulting material showed an ability to bind inorganic cations and biogenic amines in a concentration-dependent manner. The similarity of the uptake curves, the identical uptake maxima and the narrow pH range (between 4-7) over which the uptake of the inorganic and organic cations took place indicated a binding of these ions to common sites. In addition, the fact that all the uptake curves fitted the Rothmund-Kornfeld equation for cation exchangers corroborated the cation exchanger properties of the dialyzed granule material. The CA binding capacity corresponded to 20-30% of the normal CA content of bovine medullary granules.

Adenosine Triphosphate↗
PubMed1976

In vitro uptake of 5-hydroxytryptamine and dopamine by rat mast cells after exocytosis induced by antigen or compound 48/80.

Mast cells from the peritoneal and pleural cavities of actively sensitized rats were isolated and incubated with biogenic amines (5-hydroxytryptamine and dopamine) with or without pretreatment with specific antigen. An anaphylactic reaction resulting in the release of 20-25% of the histamine in the cells led to a slightly reduced amine uptake. At concentrations which induced histamine release comparable to that during the anaphylactic reaction compound 48/80 had a similar effect on the uptake of the two amines. Histamine release induced by higher concentrations of compound 48/80 led to a more pronounced reduction in the uptake of the amines, the reduction being roughly proportional to the extent of the histamine release. It is concluded that the reduction in the in vitro amine uptake after anaphylactic and compound 48/80-induced histamine release is due to the fact that there are a fewer intact granules capable of storing histamine and not primarily due to a damage to the mechanisms by which mast cells take up biogenic amines in vitro. The observations further strengthen the view that anaphylactic and compound 48/80-induced histamine release are non-cytolytic processes.

Anaphylaxis↗
PubMed1976

Quantitative aspects of the vagal control of gastrin release in cats.

Gastrin concentrations were measured in the gastric blood of eviscerated cats. Blood flow was recorded concomitantly thus enabling quantitative determination of the gastrin output. Electrical vagal stimulation within the "physiological" frequency range (0.5-3 Hz) did not regularly result in any detectable changes in the peripheral gastrin level but an increase in this level was always observed on stimulation with frequencies above 3 Hz. A constant gastrin release per stimulus was then obtained, as long as the total number of vagal stimuli did not exceed 2,000-3,000. A larger number of impulses resulted in rapid fatigue of the release mechanism, indicating either a rapid and sustained fatigue of the neural control mechanism or the existence of a rather small pool of gastrin for immediate release-amounting to less than one per cent of the total antral store of immunoreactive gastrin. The rate at which such a releasable pool was refilled would suffice to compensate for the depletion induced by vagal stimuli at physiological frequencies i.e. less then 3-4 Hz only. The two vagi innervate separate gastrin pools, which behave independently as far as release and refilling are concerned.

Animals↗
PubMed1976

An in vitro-formed protamine-heparin complex as a model for a two-compartment store for biogenic amines.

The capacity of an in vitro-formed protamine-heparin complex (PHC) to store inorganic cations and biogenic amines was investigated. The PHC behaves like a two-compartment storage system. One compartment corresponds to the terminal free carboxyl groups of the protamine moiety and has the characteristics of a cation exchanger, with the ability to bind inorganic cations and biogenic amines in a reversible and rather unslective manner. The cations and biogenic amines therefore compete for and displace each other from the common ionic binding sites. The binding sites in the other compartment, corresponding mainly to the carboxyl groups of the heparin moiety, are only unmasked at high ionic concentrations and show a specific affinity for biogenic amines. The storage of amines in this compartment of the PHC is reversible but is dependent not only on simple ionic binding but evidently also on other attractive forces, such as dipole and hydrogen bonding.

Binding Sites↗