bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations on stretch reflexes in lumbar back muscles of the cat
Authors: Carlson Hans
Published: December 2008

Reflex responses to brief muscle stretch and to electrical stimulation of dorsal roots were studied in cat longissimus and iliocostalis muscles by myographic and electromyographic recordings in spinal and anesthetized preparations. Brief stretch applied simultaneously to both muscles, by pulling at an isolated segment of the iliac bone, elicited contractions only in the central region of longissimus, composed of slowly contracting fibers, the time to peak tension varying between 70 and 100 ms. No reflex responses were observed in the faster contracting parts of this muscle or in the iliocostalis under the stimulation conditions used. The total reflex time usually varied from 4.5 to 7 ms which is shown to correspond to intraspinal conduction times, approximately between 2 and 5 ms. Only exceptionally was a central reflex delay corresponding to a monosynaptic transmission observed. Reflexes evoked by dorsal root stimulation (L4, L5) have a central conduction time similar to those elicited by adequate stimulation. The possibility that the central pathway for stretch reflexes in longissimus may involve more than two neurons is considered. In decerebrate preparations the central region of longissimus displays a prominent tonic stretch reflex. With the longissimus in situ the magnitude of the reflex is highly dependent on the position of the lumbar spine relative to the pelvic girdle.
Contralateral influence on recruitment of curarized muscle fibres during maximal voluntary extension of the legs
Authors: Secher Niels H. , Rørsgaard Susanne , Secher Ole
Published: December 2008

The force of maximal voluntary contraction (MVC) was compared during extension of one leg alone and during simultaneous extension of both legs. In 6 subjects MVC of two leg extension was 75 + 3.6 (S.E.) % of the sum of the single one leg MVC. This may indicate a reduced muscle fibre involvement during two leg extension as compared with one leg extension. We investigated the possibility that either red (type I) or white (type II) muscle fibre recruitment was restricted during two leg extension. The neuromuscular transmission in the two types of fibres was partially blocked with d‐tubocurarine (dtc) or decamethonium (C10) for either type 1 or II, respectively. In 5 subjects receiving dtc the ratio between the reduced two leg and one leg extension forces (75 ± 2.3%) did not change. During administration of C10, however, this ratio decreased by 16 ± 3.1 %. Partial blocking with dtc caused a two component curve during tension development with a first maximum at 0.22 s, and another maximum at 1.03 s of a 3 s attempt to reach MVC. During partial blocking with C10 the first maximum disappeared indicating human fast twitch fibres to be blocked by C10. Thus, partial blocking with C10 results in muscle contractions where a relatively large amount of type I muscle fibres are contributing to the force developed. The experiment suggests that type I fibre recruitment is restricted during severe static exercise in normal muscles. Furthermore, it demonstrates that fibre recruitment can vary in the same muscle function performed with one leg or two legs.
Ultrastructural evidence for an innervation of epithelial enterochromaffine cells in the guinea pig duodenum
Authors: Lundberg Jan M. , Dahlström Annica , Bylock Anders , Ahlman Håkan , Pettersson Gösta , Larsson Inger , Hansson Hans‐Arne , Kewenter Jan
Published: December 2008

The innervation of the duodenal enterochromaffine cells (E.C.) of the guinea pig was studied at the electronmicroscopic level. Pretreatment with 5‐OH‐dopamine was performed to visualize catecholaminergic (CA) nervous elements. Near the basement membrane of all examined E.C. in the crypts, bundles of unmyelinated nerve processes were observed, only partly ensheathed in a Schwann cell cover. At least 4 types of processes could be observed. 1) Boutons containing only small clear vesicles, probably cholinergic fibres; 2) boutons with small clear vesicles, and in addition large (200 nm) granules with a dense matrix (P‐type‐fibres); 3) boutons with small electron‐dense vesicles, probably CA‐fibres; and 4) processes with few vesicles but having the appearance of dendrites. No typical synaptic arrangements were observed, but the minimal distance between the E.C. and the nerve bundles was 150 to 250 nm, thus well within the functional limits of the “autonomic gap”. Thus, epithelial E.C. may be influenced by several types of nervous elements, including CA‐fibres.
Nervous control of blood flow in the dental pulp in dogs
Authors: Heyeraas Tønder K. , Næss G.
Published: December 2008

Pulpal blood flow (PBF) was measured by H2‐gas clearance in 30 dogs during electrical nerve stimulation, denervation and close intraarterial infusion of noradrenaline (NA). Electrical stimulation of the cervical sympathetic nerve and NA infusion always resulted in decreased PBF. The constrictor effect was reduced by α‐blockers, but was never abolished or reversed to a vasodilation. Thus, no evidence for β‐receptors in the dental pulp blood vessels was found. The fall in PBF produced by cervical sympathetic stimulation could be prevented by cutting the inferior alveolar nerve in the mandibular canal. Stimulation of the cut inferior alveolar nerve in the mandibular canal produced variable pulpal flow changes: Both a marked increase and decrease were measured. The flow changes during inferior nerve stimulation were unaffected by α‐receptor blockade, while atropine reduced the vasoconstrictor respons or augmented the dilatory response. Electrical stimulation of the mandibular nerve before its entrance in the canal caused vasodilation, proposing a sensory antidromic axonreflex in the dental pulp. Sympathetic denervation had little or no effect on PBF, while cutting of the inferior alveolar nerve in the canal increased PBF in lower canine from 0.159 to 0.219 ml/min. g. The experiments show that pulp blood vessels of the dog may be controlled by both vasodilator and vasoconstrictor nerve fibers.
Frequency selectivity of the peripheral auditory analyzer studied using broad band noise
Authors: Møller Aage R.
Published: December 2008

The sharpness of the frequency tuning of single auditory nerve fibers was studied in the rat on the basis of responses to broad band noise. The cross‐spectra between the sound stimulus and the sound‐to‐stimulus locked discharge rate were used as estimates of the transfer functions of the peripheral auditory analyzer. The sharpness of the tuning obtained in that way was measured as Q3db and Q10db It was found that these Q‐values decreased with increasing stimulus intensity but that the decrease was different when it was based on measurements at 3 dB points of the obtained transfer functions compared with measuring it at 10 dB points. The change in width was less for fibers with low CF. In all the fibers studied the frequency of maximal response (CF) decreased with increasing sound intensity. The implication of these findings for pitch perception and for noise induced hearing loss is discussed.
The relationship between cortical recruiting responses and ponto‐geniculo‐occipital waves during paradoxical sleep in the cat
Authors: Laihinen A. , Valleala P.
Published: December 2008

In an earlier study it was found that during paradoxical sleep (PS) thalamo‐cortical recruiting responses (RRs) and rapid eye movements usually did not appear simultaneously. As shown elsewhere, ponto‐geniculo‐occipital (PGO) wave activity and rapid eye movements are during PS closely related to each other in time. Similarly, in the present study it was observed that during paradoxical sleep in cats in which the center median nucleus of the thalamus was being stimulated at a rate of 7–9 Hz PGO waves in the geniculate nuclei did not in the rule occur in the presence of RRs recorded from the motor cortex. This effect was most pronounced with respect to series of PGO waves which usually occur at a rate of 4–7 Hz. On the basis of these experiments it was concluded that PGO waves and RRs are reciprocal events and mutually exclusive. Considering the well‐known fact that RRs represent synchronization. this negative correlation between RRs and PGO waves indicates that the desynchronizing tendency typical to paradoxical sleep is most pronounced during the occurrence of PGO waves.
The influence of scrotal warming on testicular blood flow and endocrine function in the rat
Authors: Damber Jan‐Erik , Janson Per Olof
Published: December 2008

The effects of local heating on testicular and epididymal vascular resistance in sodium pentobarbitone anesthetized rats was measured with a microsphere technique. When exposing the left scrotum to 33 and 37°C for 30 min. no significant effects on blood flows were observed in comparison to those of the right side. Exposure to 41°C caused a significant (p<0.05) decrease in vascular resistance of both testes and epididymides. The response was more pronounced at 4°3. The Leydig cell function, as judged from the testosterone concentrations in plasma and testicular tissue after LH stimulation, was significantly (p<0.01) depressed at 41 and 43°C. It was concluded that the impaired Leydig cell function was unrelated to testicular blood flow.
Studies on calcium uptake by myornetrial microsomes with particular reference to the dependence on inorganic phosphate and oxalate
Authors: Batra S.
Published: December 2008

Ca uptake by microsomes isolated from non‐pregnant rabbit myometrium was potentiated by both inorganic phosphate (Pi) and oxalate anions. Both Piand oxalate bad little effect on the initial rate of uptake but a pronounced effect on the capacity of Ca uptake measured after 20 min which was greater in the presence of oxalate than that of Pi (5 mM each). The presence or absence of sucrose in the uptake medium had a significant effect on oxalate‐induced potentiation of Ca uptake but not on that potentiated by Pi or that measured in the absence of either potentiating anion. A part of Ca accumulated additionally under the influence of sucrose could be removed by washing microsomes with KCI.

Another significant difference between the pontentiating effect of oxalate and Pi was observed when the pH of the incubation medium was varied. In the presence of oxalate the pH optimum was between 6.46.8, whereas that in its absence or in the presence of Pi the optimal pH was around 7.2. Reduction in pH from 7.2 to 6.8 along with the substitution of KCI by sucrose resulted in 3‐fold increase in Ca uptake when oxalate was used as the potentiating anion. The results suggest that Ca is taken up by a different mechanism in the presence of oxalate than that in its absence or when oxalate anion is substituted with inorganic phosphate.
Oxidative and lysosomal capacity in skeletal muscle of mice after endurance training of different intensities
Authors: VIHKO VEIKKO , SALMINEN ANTERO , RANTAMAKI JARI
Published: December 2008

The activity of certain enzymes of energy metabolism (cytochrome c oxidase, citrate synthase, malate dehydrogenase, and lactate dehydrogenase) and of lysosomes (β‐glucuronidase, β‐N‐acetylglucosaminidase, arylsuphatase, ribonuclease, deoxyribonuclease, acid phosphatase, and cathepsin D) was assayed from m. rectus femoris of mice trained 5 days per week, 1 h per day for 4 weeks according to 4 different programmes: I. running speed 20 m/min, horizontal track, II. 25 m/min, horizontal track, III. 20 m/min 8° uphill inclination, and IV. 25 m/min 8° uphill inclination. Oxidative capacity increased and anaerobic capacity decreased without distinction between the different training programmes. Of acid hydrolases assayed the activities of β‐glucuronidase and cathepsin D were increased independently of training intensity. Simultaneous histochemical observations on β‐glucuronidase and arylsulphatase activities in the contralateral m. rectus femoris showed more intense staining in red as compared to white muscle fibres. It is suggested that training affected the red fibres and that the applied level of loading was probably too low to cause major involvement of white fibres.
Redox state ol the cellular free NAD pools, phosphorylation state of the adenylate system and the (Na+‐K+)‐stimulated ATP‐ase in rat liver
Authors: Kinnula Vuokko L. , Hassinen Ilmo
Published: December 2008

The effect of hypoxia (30 min 10% or 8%, O2,) on the phosphorylation state and redox state of the cytosol and mitochondria of rat liver were studied. Measurements were made both from normal animals and animals which had been exposed to the reduced partial pressure of oxygen (50.5 kPa or 40.8 kPa of air) for one or seven days. Cytosolic free NAD was reduced in the liver both in acute hypoxia and in hypoxia after one or seven days,i.e. the lactate/pyruvate and sn‐glycerol‐3‐phosphate/dioxyacetonephosphate ratios increased markedly. A marked reduction in the mitochondrial free NAD pool occurred only in acute hypoxia and only a slight reduction was observed in animals kept at 40.8 kPa for one or seven days, as evaluated from the hepatic hydroxybutyrate/acetoacetate ratio. Liver ATP concentration decreased rapidly in acute hypoxia without any significant recovery during one or seven days at 40.8 kPa. The hepatic ATP/ADP× Piratio decreased significantly, with a simultaneous decrease in the total adenine nucleotide concentration. A tendency was observed for the ATP/ADP× Piratio to return to normal after seven days,i.e. the values in acute hypoxia were significantly smaller than those noted in hypoxia after seven days, demonstrating an adaptation of the energy metabolism during prolonged hypoxia. Hepatic (Na+‐K+)‐stimulated ATP‐ase activity was not affected by hypoxia.
Effect of metabolic inhibitors on phenylalanine influx in cerebral cortex slices from mature and immature rats
Authors: Laakso Maija‐Liisa
Published: December 2008

Earlier investigations have shown that the transport of aromatic amino acids into cerebral cortex slices of rats changes during ontogenetic development. In order to illuminate the possible influence of the developmental alterations of energy metabolism in the brain on the changes of the amino acid transport the influx of phenylalanine into cerebral cortex slices of adult and 7‐day‐old rats was measured in the presence of metabolic inhibitors. Also the levels of lactate, ATP, ADP, AMP and creatine phosphate in the slices were measured. The used inhibitors cyanide, dinitrophenol and iodoacetate, which disturb certain steps of energy metabolism, had very similar effects in both age groups on phenylalanine influx and on the levels of energy‐rich phosphates. The correlation between the level of ATP and the influx of phenylalanine was positive in both age groups, but the slopes of the regression lines were different. If ATP supplies energy for amino acid transport, its utilization, rather than its availability is a limiting factor in the slices from 7‐day‐old rats. Developmental changes in energy metabolism seem to have a minimal role in the changes of amino acid transport during the maturation of the brain. Changes in the properties of cell membrdne carriers and in the transmembrane ionic gradients may be more important.
Further evidence for the involvement of microtubules in the proximo‐distal intra‐axonal transport of acetylcholine and related enzymes in rat sciatic nerve
Authors: Heiwall P.‐O. , Larsson P.‐A. , Dahlström A.
Published: December 2008

The two mitotic inhibitors colchicine (COL) and podofyllotoxin (POD) and their respective isomers, IumiCOL and picropodofyllin (picPOD) were tested for their effect on the intraaxonal transport (AXT) of acetylcholine (ACh) and the cholinergic enzymes in rat sciatic nerve. The mitotic inhibitors and their isomers were dissolved in saline + 10%, ethanol (COL and lumiCOL) or dimethylformamid (DMFA) (POD and picPOD) and injected (3–5 γl) subepineurally into the sciatic nerve. As controls the vehicle (saline+ 10% ethanol or DMFA) alone were injected into some rats. 2 h later a crush operation was performed 15 mm distal to the site of injection. The accumulation of ACh or the two enzymes, ACh‐esterase (AChE) and cholineacetyltransferase (CAT), in the nerve segment proximal to the crush (12 h before death) was used as a measure of the AXT. COL and POD were very effective in inhibiting AXT of all 3 substances, while their isomers, lumiCOL and picPOD, were essentially without effect on AXT in equimolar concentrations (0.1 M). The effects on AXT of the 4 test substances thus appear related to their affinity to bind to tubulin, which is several orders of magnitude higher for COL and POD than for their isomers. The results further support the view that intact microtubules are essential for AXT of both membrane‐bound (AChE) and soluble (CAT) enzymes, as well as of ACh in rat motor nerves.
Thyrotropin‐releasing factor: Distribution in neural and gastrointestinal tissues
Authors: Leppäluoto J. , Koivusalo F. , Kraama R.
Published: December 2008

Specimens of several rat tissues were purified with methanol extraction, gel filtration and cation exchange chromatography and measured for thyrotropin‐releasing factor (TRF) concentration by radioimmuno‐assay. TRF immunoreactivity of neural tissues (hypothalamus, spinal cord, medulla, cerebrum and cerebellum) and gastrointestinal tissues (pancreas, stomach, duodenum and colon) behaved as synthetic TRF during the purification. This dual distribution suggests that TRF‐secreting cells have their origin in the embryonal neuroectoderm.
Plasma vasopressin in ethanol intoxication and hangover
Authors: Linkola Jaakko , Ylikahri Reino , Fyhrquist Frej , Wallenius Marja
Published: December 2008

The effect of ethanol intoxication and hangover on immunoreactive plasma arginine vasopressin (AVP) concentration was studied in 7 healthy supine men in controlled clinical conditions. In 6 subjects plasma AVP increased above control values at the time of maximal blood ethanol Concentration. The highest AVP values were observed in the subjects having nausea and vomiting and the worst hangover symptoms. During hangover plasma AVP values were higher than the controls and the response of plasma AVP to upright posture was exaggerated. The dissociation of plasma AVP concentration and ethanol diuresis suggested that the suppression of AVP release is not the sole determinant of ethanol diuresis. The study may indicate that the toxic effects of ethanol and the severity of hangover symptoms are associated with the state of hydration and individual sensitivity of AVP triggering mechanisms.
Reflex adrenergic control of endocrine pancreas evoked by unloading of carotid baroreceptors in cats
Authors: Järhult Johannes , Holst Jens Juul
Published: December 2008

The effects of unloading of the carotid baroreceptors on arterial plasma glucose concentration as well as on portal plasma immunoreactive glucagon (IRG) and insulin (IRI) concentrations were studied in an‐estethized, vagotomized cats either by sectioning the sinus nerves or by lowering the pressure in the isolated carotid sinuses. Complete elimination of the carotid baroreceptor discharge by cutting the sinus nerves caused an increase in the arterial plasma glucose concentration by 100% and an increase in the portal IRG level by about 200%, whereas the portal IRI concentration decreased to 50% of its basal value. These baroreceptor‐induced changes of the plasma IRG and IRI levels seemed to be graded in relation to the drop in carotid blood pressure and they were clearly detectable when the pressure was lowered from 120 to 90 mmHg in the isolated carotid sinus preparation. The described reflex hyperglycemia, hyperglucago‐nemia and hypoinsulinemia were mediated to the pancreas and liver mainly by the sympatho‐adrenal system, since cutting the splanchnic nerves above the adrenal glands abolished the hyperglycemic and hypoinsulinemic responses and markedly depressed the magnitude of the hyperglucagonemic response. In adrenalectomized cats, complete unloading of the baroreceptors evoked both hyperglucagonemia and hypoinsulinemia although the magnitude of the hormonal responses was diminished. In animals where the pancreas and liver were sympathectomized but the adrenal glands left intact, cutting the sinus nerves evoked a doubling of the IRG level and a slight increase in plasma glucose, but no significant change of the IRI level. I.v. infusion of adrenaline (1 γg/kg × min) or noradrenaline (5 γg/kg × min) caused pronounced increases in IRG and plasma glucose and a clear‐cut reduction of IRI. We conclude that the function of the endocrine pancreas in the cat can be influenced by variations in the blood pressure by means of a reflex control which originates from arterial baroreceptors. This reflex adjustment of the endocrine pancreas is mediated chiefly by two links of the sympatho‐adrenal system, namely by catecholamine‐release from the adrenal medulla and, more importantly. by a direct adrenergic nerve fibre influence on the α‐ and β‐cells.
Differential effect on the sympathetic transmitter level in uterus and other organs of guinea‐pig by drugs interfering with adrenergic nerve functions
Authors: Thorbert G. , Alm P. , Owman Ch. , Rosencren E. , Sjöberg N.‐O.
Published: December 2008

5 types of adrenergic blocking agents with different modes of action were administered and the rate of transmitter depletion was studied in different uterine regions of guinea‐pig, and compared with that in the heart and submandibular gland by a combination of fluorescence histochemical and spectrofluorimetric methods. The tyrosine‐hydroxylase inhibitor, H 44/68, as well as reserpine and guanethidine, produced a more efficient reduction in neuronal noradrenaline in the heart and submandibular gland than in the uterus. A differential action on the sympathetic transmitter, though less clearcut, was seen with 6‐hydroxydopamine. The noradrenaline‐depleting effect of metaraminol did not distinguish between those adrenergic nerves supplying the uterus from those of the control tissues. It is suggested that the differential effects may be related to a lower activity in the uterine adrenergic nerve system, probably because this system is to a large extent composed of short adrenergic neurons, which appear to have a particularly slow transmitter turnover.
Effect of intraantral pH on basal gastrin release into the circulation and antral lumen in anesthetized cats
Authors: Uvnås‐Wallensten Kerstin
Published: December 2008

Uvnås‐Wallensten, K. Effect of intraantral pH on basal gastrin release into the circulation and antral lumen in anesthetized cats. Acta physiol. scand. 1978. 104. 386–393.

In acute experiments on cats antral pouches were perfused with solutions of different pH (1–13). After antrum passage the gastrin levels in the perfusates were measured with radioimmunoassay and the amounts of gastrin released into the antral lumen per minute calculated. The venous gastrin levels were determined concomitantly. Small amounts of gastrin (1 000–1 500 pg/min) were released into the antrum during perfusion with 0.1 M HCI. Subsequent perfusion with 0.15 M NaCl (pH 6.8) did not significantly increase the release of gastrin. On the other hand, 0.1 M phosphate buffer (pH 7.4) caused a dramatic augmentation of the gastrin output into the antral lumen (˜17 fold). A concomitant increase of peripheral gastrin levels was observed. Also other alkaline solutions such as 0.15 M NaHCO, (pH 8), 0.15 M Tris buffer (pH 8) or 0.01 and 0.1 M NaOH (pH 12 and 13) promoted the release of gastrin. It is discussed whether the gastrin release at alkaline pH is induced by the alkaline pH itself or by anions such as HPO‐4 HCO‐3 and OH‐. The apparent effect of pH could then be due to the formation of these ions at higher pH.
Effects of acetylcholine, noradrenaline, and prostaglandins on the isolated, perfused human fetal urethra
Authors: Anderson K.‐E. , Person C. G. A. , Alm P. , Kullander S. , Ulmsten U.
Published: December 2008

Anderson, K.‐E., C. G. A. Person, P. Alm, S. Kullanderand U. Ulmsten,Effects of acetylcholine, noradrenaline, and prostaglandins on the isolated, perfused human fetal urethra. Acta physiol scand. 1978.104. 394–401.

Preparations of the isolated bladder‐urethral junction obtained from human fetuses at midgestation were suspended in Krebs solution (37°C), and the urethral lumen was perfused at a low rate (2 ml/h). Resistance to flow and changes in longitudinal tension were recorded. In additional experiments, isometric tension changes were recorded in isolated detrusor strips. The occurrence of adrenergic nerve terminals was investigated by the fluorescence technique of Falck and Hillarp. Acetylcholine (0.1‐1.0 μg/ml) produced a concentration‐related increase in longitudinal tension and in resistance to flow; the effects were unaffected by phenoxybenzamine (0.1μg/ml), but completely inhibited by atropine (0.1μg/ml). The effect on tension was more marked than that on resistance to flow. Noradrenaline (0.005‐1.0μg/ml) also produced a concentration related increase in longitudinal tension and in resistance to flow; the effects were abolished by phenoxybenzamine (0.1μg/ml). The amine had a more pronounced effect on resistance to flow than on longitudinal tension. ProstaglandinF2α(0.1‐0.5μg/ml) increased longitudinal tension and resistance to flow; the effects were not antagonized by atropine (0.1 pg/ml) or by phenoxybenzamine (0.1μg/ml). In preparations contracted by noradrenaline or acetylcholine, prostaglandinsEland E, (0.02‐0.2μg/ml) decreased resistance to flow and longitudinal tension. Acetylcholine (0.02‐0.2μg/ml) and prostaglandin F2α(0.0‐0.5μg/ml) contracted, noradrenaline (0.05‐0.5μg/ml) relaxed, and prostaglandin Eland E2(0.1–5.0μg/ml) had no consistent effects on the detrusor strips. Histochemically, no adrenergic nerve terminals could be demonstrated in the detrusor. bladder neck or urethra.
Inhibition of compound 48/80‐induced intradental sensory nerve activity by disodium cromoglycate and serotonin antagonists
Authors: Olgart Leif , Gazelius Bertil
Published: December 2008

Olgart, L. and B. Gazelius, Inhibition of compound 48/80‐induced intradental sensory nerve activity by disodium cromoglycate and serotonin antagonists. Acta physiol. scand. 1978. 104. 415–421.

Local application of compound 48/80 induced long lasting nerve activity in intradental sensory nerves in the teeth of cats and dogs. This effect was inhibited by pretreatment with disodium cromoglycate (DSCG) given locally (2 × 10‐2 M) or i.a. (20 mg/min). DSCG did not have any effect on the nerve excitability per se, as judged from the responses to hypertonic NaCl and air blasts applied to exposed dentin before and after administration of DSCG. Local treatment with lysergic acid diethylamide (0.1‐1 mg/ml) and methysergide (0.05‐0.5 mg/ml) selectively reduced or inhibited the compound 48/80 induced nerve activity. Systemic administration of methysergide (12.5 μglkg) prevented the excitatory effects of compound 48/80 but was without effect when administrated during a state of established activity. The present findings support the hypothesis that compound 48/80 has an indirect effect on intradental sensory nerves and indicate that vascular reactions take part in intradental sensory nerve excitation.
Effects of hyperinsulinemia on lactose secretion and glucose uptake by the goat mammary gland
Authors: Hove Knut
Published: December 2008

Hove, K. Effects of hyperinsulinemia on lactose secretion and glucose uptake by the goat mammary gland. Acta physiol. scand. 1978. 104. 422–430.

Lactose secretion by goat mammary glands was studied after intra‐arterial infusions of insulin and/or glucose causing rises in plasma insulin concentrations in mammary venous blood of about 3–5 mg/ml. Such levels are sufficient to strongly stimulate insulin sensitive processes when present in the systemic circulation. Two goats with mammary glands in situ and two with one of the glands autotransplanted to the neck were used for the experiments. Increasing the insulin concentration in blood to the mammary gland induced a decrease in lactose yields during a 3 h infusion (p < 0.02). Simultaneously arterial plasma glucose decreased by 15–20 mg/100 ml to about 50 mg/100 ml. When the systemic hypoglycemic effect of the insulin infusion was offset by a simultaneous intra‐venous infusion of glucose, no significant change in lactose secretion was observed during 8 hours of hyperinsulinemia. No change in mammary glucose uptake as measured by mammary blood flow x mammary arterio‐venous glucose differences could be detected. (Average glucose uptake for 2 h before infusion: 30.9 mg/min; during 8 h of infusion: 31.2 mg/min.) It may be concluded that increased levels of insulin in the blood perfusing the mammary gland did not affect mammary glucose uptake or lactose synthesis as long as blood glucose was maintained at normal levels. The results therefore indicate that the glucose turnover in mammary glands, which in high yielding dairy ruminants represents the main organ of glucose utilization in the body, is in fact independant of changes in plasma insulin concentrations.
The distribution and secretion of kallikrein in some exocrine organs of the rat
Authors: ØRstavik Torill Berg
Published: December 2008

ørstavik, T. B. The distribution and secretion of kallikrein in some exocrine organs of the rat. Acta physiol. scand. 1978. 104. 431–442.

Extractable kallikrein was quantitated in the submandibular, sublingual, and parotid glands and in the pancreas. No kallikrein was detected in the exorbital lacrimal glands and tears. The highest kallikrein concentrations (EU/ml) were in all major salivary gland secretions seen after α‐adrenergic stimulation, less after β‐adrenergic and least after parasympathetic stimulation. When taking into account the large variations in salivary flow rate, α‐adrenergic stimulation was in the parotid and particularly in the submandibular gland found to result in the highest kallikrein secretory activity measured by the kallikrein secretory rate (EU/ min). This shows that the kallikrein‐rich granular tubular cells are selectively activated through α‐adrenergic sympathetic receptors. The differences observed in the parotid saliva were small and not always statistically significant. However, when cervical nerve stimulation was superimposed upon parasympathetic stimulation, kallikrein secretory rate as well as kallikrein concentration increased. The large individual variations in salivary gland kallikrein content and secretion and the rather small differences observed in kallikrein secretory rate after nervous stimulation of the parotid and sublingual glands, may indicate that the kalli‐krein‐containing striated ducts are also influenced by factors other than the secretory nerves. The kallikrein concentration and secretory rate in urine was studied. A strong positive correlation between kallikrein secretory rate and fluid volume was found in urine but not in saliva.
Adenosine and cyclic AMP in cerebral cortex of rats in hypoxia, status epilepticus and hypercapnia
Authors: Rehncrona Stig , Siesjö Bo K. , Westerberg Eva
Published: December 2008

Rehncrona, S., B. K. Siesjöand E. Westerberg,Adenosine and cyclic AMP in cerebral cortex of rats in hypoxia, status epilepticus and hypercapnia. Acta physiol. scand. 1978.104. 453–463.

The influence of hypercapnia, hypoxia and status epilepticus on cerebral cortex concentrations of adenosine, adenine nucleotides and cyclic AMP was studied on lightly anaesthetized (70% N2O) and artificially ventilated rats. Neither hypercapnia (arterial Pco2about 80 and about 300 mmHg) nor hypoxia (minimal values of 19 mmHg) altered tissue concentrations of AMP, cyclic AMP or adenosine. Bicuculline‐induced status epilepticus was accompanied by increased concentrations of cyclic AMP but adenosine concentration did not change. Experiments with ischemia, and those in which tissue hypoxia was exaggerated by unilateral carotid artery ligation, showed that tissue adenosine concentrations were elevated only when AMP concentrations rose. It is concluded that the marked increase in cerebral blood flow which occurs in hypoxia and status epilepticus is unrelated to changes in tissue adenosine concentration and that the increase in cyclic AMP during neuronal hyperactivity is triggered by other mechanisms than adenosine accumulation.
Release of substance P‐like immunoreactivity into the antral lumen of cats
Authors: Uvnäs‐Wallensten K.
Published: December 2008

Uvnas‐Wallensten, K. Release of substance P‐like immunoreactivity into the antral lumen of cats. Acta physiol. scand. 1978.104. 464468.

SPLI can be detected in antral perfusates of cats. Experiments were performed in anesthetized cats provided with antral pouches. The pouches were perfused with 0.1 M HCI and 0.15 M NaCl. The concentration of SPLI in the perfusates was determined by radioimmunoassay. Basal output varied between 0–60 pp/min. Electrical vagal stimulation (2–10 Hz) caused release responses varying between 100–800 pg. Ach given i.v. or intraantrally also released SPLI into the antral lumen as well as adrenaline given i.v.
Inhibition of acetylcholine release in guinea pig ileum by adenosine
Authors: Gustafsson Lars , Hedqvist Per , Fredholm Bertil B. , Lundgren Cösta
Published: December 2008

Gustafsson, L., P. Hedqvist, B. B. Fredholmand G. Lundgren,Inhibition of acetylcholine release in guinea pig ileum by adenosine. Acta physiol. scand. 1978.104. 469–478.

The effect of adenosine on cholinergic neuroeffector transmission was studied in the isolated guinea pig ileum. Adenosine caused a dose‐dependent and inverse frequency‐dependent inhibition of contraction responses to transmural nerve stimulation. Blockade of adrenergic neurotransmission did not alter the inhibitory effect of adenosine. Adenosine also inhibited contraction responses to serotonin, angiotensin and high potassium, but not the responses to acetylcholine, histamine or direct electrical stimulation of the smooth muscle cells. Adenosine had little effect on basal outflow of acetylcholine but inhibited markedly and reversibly the release of acetylcholine induced by nerve stimulation. Acetylcholine was determined with gas chromatography‐mass spectrometry. The results provide direct evidence that adenosine inhibits cholinergic neuroeffector transmission in the gut by a prejunctional action on acetylcholine release. This may be of functional importance since adenine compounds are released during stimulation of intestinal nerves.
Studies on the melanin‐affinity of metal ions
Authors: Larsson Bengt , Tjälve Hans
Published: December 2008

Larsson, B. and H. Tjälve, Studies on the melanin‐affinity of metal ions. Acta physiol. scand. 1978. 104. 479–484.

Melanin has a capacity to accumulate metal ions in vivo and in rim. In the present study, the relative melanin‐affinity of various metal ions has been determined in vim by use of the bisquaternary ammonium compound paraquat as a reference ion. Paraquat has previously been shown to bind to melanin with ionic binding as the dominant mechanism of interaction. The relative melanin‐affinity of the metal ions was determined by studying the ability of the metal ions to compete with paraquat for combining with the melanin. Pigment from beef eyes and synthetic melanin prepared from L‐DOPA with tyrosinase were used. The affinity for melanin of the metal ions increased with increasing valencies. The order of affinity of the alkali metals was Cs+:> Rb+ ‐> K+ > Na+ > Li+ and of the alkaline earth metals Ba2+ > Sr2+ > Ca2+ > Mg2+. T1+ had a slightly higher affinity than the alkali metals. Pb2+ had the strongest affinity of the divalent cations and Cu2+ was next in order. Ni2+, Co2+ and Mn2+ showed affinities in the mentioned order. La3+ and Gd3+, which are chemically similar although the former is diamagnetic and the latter paramagnetic, showed a similar affinity for the melanin, suggesting that it is the chemical and not the magnetic properties which determine the affinity. The studied metal ions showed the same order of affinity for the synthetic melanin as for the eye‐melanin, suggesting that the protein moiety of the pigment granules plays a minor role in the binding of the metal ions. Melanin has been shown to contain numerous free carboxyl groups. The results are consistent with the hypothesis that the metal‐ion binding of the melanin can be ascribed to a cation‐exchange activity with the free carboxyl groups in the melanin polymer as the main binding‐sites.
Sympathetic innervation of the urinary bladder and urethral muscle in the pig
Authors: Larsen Jens‐Jørgen , Nordling Jørgen , Christensen Bjørn
Published: December 2008

Larsen, J.‐J., J. Nordling and B. Christensen, Sympathetic innervation of the urinary bladder and urethral muscle in the pig. Acta physiol. scand. 1978. 104. 485–490.

The sympathetic innervation of the lower urinary tract was studied in the female and male pig using a specific histochemical technique for visualization of noradrenaline containing nerves. In smooth muscle from the detrusor few evenly distributed adrenergic nerve terminals were found. A greater number of terminals were observed in the trigone, bladder neck and urethra. There was no sex difference. In smooth muscle specimens from pig detrusor and trigone sympathetic nerve terminals were more abundant than in corresponding tissue from humans.
Anaphylatoxin‐induced shock and two patterns of anaphylactic shock: Hemodynamics and mediators*
Authors: Pavek K. , Piper Priscilla J. , Smedegârd G.
Published: December 2008

In the dog, différent cardiorespiratory reactions were identified in two types of anaphylactic shock and in C5a‐AT (anaphylatoxin)‐induced shock. AU three types had in common a portai blood pooling with conséquent decrease in the venous return, cardiac output, and arterial pressure. In anaphylaxis (a) of the first type, at a low titer of hemagglutinating antibodies, the latent period was 68 s and heart and lung function was unchanged. In the second type, at high titer, the latency was 19 s and pulmonary hypertension and decreased heart contractility occurred. After AT injection pulmonary hypertension appeared with tachypnea and unchanged heart function. Tachyphylaxis, but not cross‐over tachyphylaxis against the anaphylactic agent and AT was observed in dogs and isolated guinea pig lungs. AT induced a tran‐sient release and a. a prolonged release of histamine, prostaglandins (PGs), and thromboxane A2 and endoperoxides from guinea pig lungs. SRS‐A was released only in a. Indomethacin inhibited AT‐induced release of PGs in guinea‐pig lungs and AT‐induced hypotension in the dog though it did not prevent the drop in cardiac output. Thèse model studies suggest that différent patterns of clinical a. can occur, depending on the type of antibodies and/or mediators involved.
Pregnancy‐induced alterations in the turnover rate of3H‐noradrenaline formed from3H‐tyrosine in guinea‐pig uterus
Authors: THORBERT G. , ALM P. , OWMAN CH. , SJÖBERG N.‐O.
Published: December 2008

The rate of noradrenaline (NA) turnover in the non‐pregnant and pregnant guinea‐pig uterus was determined after the administration of the labelled precursor, tyrosine. Endogenous NA was determined fluori‐metrically. In non‐pregnant animals the turnover of3H‐NA was slower in the uterine horns (t½= 10 h) and cervix (t½= 9 h) than in the reference organ, heart (t½= 6 h). During pregnancy (60–65 dayspost coitum)endogenous NA in the heart increased in pace with tissue weight gain; yet, in the uterus there was a drastic reduction, down to zero levels.3H‐NA turnover increased significantly in the cervix, no3H‐NA formation remained in the uterine horn (a situation resembling that following 6‐hydroxydopamine induced sympathectomy of non‐pregnant animals), and the turnover was unaltered in the heart. The observations confirm the general idea, illustrated by the results in the heart, of a functional adaptation with a constant neuron‐target relationship during increased physiological demands. They also confirm that a very peculiar and complex neuron‐target relationship develops in the uterus during pregnancy‐involving functional and structural denervation of the adrenergic nerve plexus in the uterine horn, whereas an increased activation might explain the changes in neuronal NA and its turnover in the cervix.
Effects of 4‐aminopyridine on the excitation‐contraction coupling in frog and rat skeletal muscle
Authors: KHAN A. R. , EDMAN K. A. P.
Published: December 2008

The effects of 4‐aminopyridine (4‐AP) were studied on isolated single muscle fibres of the frog and toe muscles of the rat. In both muscle preparations, 4‐AP potentiated the twitch amplitude without significantly affecting the tetanus response. There was an increase of the time to peak tension and, in frog muscle, an increased time to half relaxation. 4‐AP produced no change of the resting membrane potential. The rate of decay and, hence, the total duration of the action potential were markedly prolonged. 4‐AP did not induce contractures by itself nor did it affect the contracture induced by caffeine. The mechanical threshold was determined by measuring the contracture response to various degrees of depolarization by potassium. This threshold was not affected by 4‐AP. Twitch potentiation by 4‐AP was independent of the extracellular calcium concentration. It is concluded that 4‐AP potentiates the twitch response by increasing the release of activator calcium into the myofibrillar space by prolongation of the action potential. In addition, there may be a more direct inhibitory action of 4‐AP on the calcium re‐uptake by the sarcoplasmic reticulum in frog muscle.
Studies on the enzymatic blood‐brain barrier: Quantitative measurements of DOPA decarboxylase in the wall of microvessels as related to the parenchyma in various CNS regions
Authors: HARDEBO J. E. , FALCK B. , OWMAN CH. , ROSENGREN E.
Published: December 2008

The presence of DOPA decarboxylase in cerebral microvessels (capillaries and venules) impedes the passage of circulating amine precursors into the brain. The relative amount of DOPA decarboxylase in this trapping mechanism as compared to the parenchymaper sewas estimated in various CNS regions, measuring the formation of dopamine from L‐DOPAin vitroorin vivoin two experimental models on rats and rabbits: (1) On the basis of the treatment with a peripheral decarboxylase inhibitor (carbidopa, which inhibits also microvascular DOPA decarboxylase in the CNS) it could be calculated that the enzyme in the microvessels of the caudate nucleus (rich in catecholamine nerve terminals), cerebellum (poor in catecholamine nerves), and spinal cord comprised 25, 91 and 79 per cent, respectively, of the total enzyme activity. (2) Measurement of dopamine formation in the spinal cord following transection at the midthoracic level (which causes degeneration of the catecholamine neurons caudal to the lesion since they are all descending) indicated that a similar fraction as found in the carbidopa model, 71 per cent, of the total tissue decarboxylase activity resided in the microvessel walls. The results show that a considerable portion of tissue decarboxylase in the CNS is present in the microvessel walls, where it represents part of an enzymatic blood‐brain barrier mechanism.
Vascular anatomy and tissue osmolality in the filiform and fungiform papillae of the cat's tongue
Authors: HALLBÄCK DAN‐AXEL , JODAL MATS , LUNDOREN OVE
Published: December 2008

The vascular anatomy of the filiform and fungiform papillae of the feline tongue was studied by i.a. injection of India ink. Vascular loops of various appearances were found in the types of papillae studied, i.e. the large and the small filiform papillae and the fungiform ones. Such hairpin loops may function as counter‐current exchangers and to test this hypothesis tissue osmolality was determined in the papillae, while exposing them to various isotonic electrolyte solutions. The large filiform papillae with a vascular arrangement similar to that of intestinal villi exhibited a marked osmolar gradient from tip to base when exposed to a solution containing both glucose and sodium. If sodium and/or glucose was excluded from the solution, tissue osmolality was significantly decreased. This was also the case when the chloride ions of the solution was substituted with sulphate. The small filiform papillae are only provided with one or a few capillary loops. They exhibited a less marked osmolar gradient than the large ones and none of the different electrolyte solutions decreased the gradient. In the fungiform papillae a tissue hyperosmolality at the tip was also demonstrated. It is proposed that the papillary epithelium is provided with active transport mechanism(s) and that the papillary vessels function as countercurrent multipliers. The functional importance of these mechanisms are tentatively discussed.
Effect of splenic nerve stimulation on the contents of noradrenaline, ATP and sulphomucopolysaccharides in noradrenergic vesicle fractions from the cat spleen
Authors: BLASCHKE E. , UVNÄS B.
Published: December 2008

In order to assess the effect of splenic nerve stimulation on the contents of noradrenaline, ATP and36S‐la belled compounds in noradrenergic vesicles from the spleen, experiments were carried out on the cat spleenin situ, its frontal portion being used as control. Particulate fractions containing noradrenergic vesicles were isolated on Ficol! gradient centrifugation of homogenates from both portions of the spleen. The cats hstReceived 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 and36S (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 and36S‐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.
Formation of cadaverine in the pregnant rat
Authors: ANDERSSON ANNE‐CHARLOTTE , HENNINGSSON STIG , ROSENGREN ELSA
Published: December 2008

The formation as well as the content of cadaverine were determined in different tissues of pregnant and non‐pregnant rats. The placenta and ovary were most potent in the ability to form cadaverine. To our knowledge this is the first report of an in vitro formation of cadaverine linked to a normal physiological process, i.e. pregnancy. The highest concentration of cadaverine was found in the placenta and ovary of the pregnant rat. Treatment with aminoguanidine generally elevated the content of cadaverine, indicating a role of diamine oxidase as a regulator of diamine content.
Correlation between fluid reabsorption and proximal tubule ultrastructure during development of the rat kidney
Authors: APERIA ANITA , LARSSON LARS
Published: December 2008

Parallel functional and ultrastructural studies were performed in maturing rats in order to elucidate factors determining the development of proximal tubular fluid reabsorption. Three groups of hydropenic animals, which were 22 to 24, 28 to 32 and 40 to 45 days old, were studied. Nephron function was evaluated at the single nephron level by micropuncture technique. The ultrastructure of the developing proximal tubules was analysed by morphometric techniques following fixation of single nephrons. Kidney weight, proximal convoluted tubule length and diameter increased during postnatal development. SNGFR increased from 2.98 to 8.57 and to 20.5 nl/min in respective group of rats whereas proximal tubular fluid reabsorption Jv (a) increased from 0.15 to 0.22 and 0.34 μm3μm_2‐s _1. Parallel to the functional development the relative area of lateral and basal cell membrane increased, resulting in a constant relationship between net fluid reabsorption and the lateral and basal cell membrane area during the fourth postnatal week and then only a slight increase in this relation during the further development. The results suggest that net fluid transport during hydropenia is determined by the amount of available lateral and basal cell membranes where the transporting enzyme for sodium is located.