Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TAENIA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1991

Comparison of the presence and actions of substance P and neurokinin A in guinea-pig taenia coli.

The presence and sites of action of two closely related tachykinins, substance P (SP) and neurokinin A (NKA), were examined in the taenia coli of the guinea-pig. SP- and NKA-like immunoreactivity (LI) were demonstrated histochemically in nerve fibres supplying the taenia. Chromatographic characterization of aqueous acetic acid extracts of taenia showed only one peak of SP-LI, corresponding in retention time to authentic SP, whereas there were multiple peaks of NKA-LI, the major one of which corresponded to authentic NKA. SP-LI and NKA-LI, determined by radioimmunoassay, were in a molar ratio of SP equivalents to NKA equivalents of 8.5:1 in taenia extracts. Extrinsic denervation of the caecum had no significant effect on the concentration of either SP-LI or NKA-LI or on their immunohistochemical distributions. Both SP and NKA (10(-10) to 10(-5) M) caused contractions of the taenia that were unaffected by hyoscine (10(-6) M), mepyramine (10(-6) M) or tetrodotoxin (5 x 10(-7) M), indicating that both peptides act directly on the smooth muscle of the taenia. Contractions to SP occurred after a short, but concentration-dependent, delay, reached a peak quickly, and then decayed. In contrast, NKA caused contractions after longer latencies, the peak was reached more slowly, and the response was maintained for up to 10 min. (D-Pro2, D-Trp7,9)-SP (10(-5) M) antagonised responses to SP and NKA to a similar degree. It is concluded that both NKA and SP should be considered as transmitter candidates for non-cholinergic nerve-mediated excitation in the taenia.

Animals↗
PubMedDate not supplied

Development and ageing of intestinal musculature and nerves: the guinea-pig taenia coli.

The fine structure of taenia coli was studied by electron microscopy in guinea-pigs from birth to old age (over 2 years old). Smooth muscle cells are approximately 1,000 microm(3) in volume at birth, 2,200 microm(3) in young adults and 4,500 microm(3) in old age. Muscle growth and muscle cell enlargement continue throughout life, an increase in muscle volume of about 240 times. Differentiated muscle cells divide during development and in adults. Because mitoses are found in any part of the muscle, the tissue grows from within, rather than by addition at the ends or borders. There is progressive increase in nucleus volume, and decrease in surface-to-volume ratio and in nucleus-cell volume ratio in muscle cells. At all ages the taenia consists of a uniform population of muscle cells (apart from dividing cells); there are no undifferentiated cells, no precursor cells or myoblasts, and no degenerating cells. Interstitial cells and fibroblasts are observed at all ages with only small variations in relative number. The amount of intramuscular collagen increases in old age. There is roughly one capillary for every 170 muscle cell profiles at birth, and one for every 200 in adults and in old age. The innervation is dense and reaches all parts of the muscle. In adults there are approximately 1,300 axons per 10,000 microm(2) of sectional area, or between 8,000 and 38,000 axons in a full cross section of taenia; this amounts to approximately 2% of the muscle volume. An answer to the question of why there are so many nerves in the taenia was not found. Expanded axon profiles are part of typical varicose fibres. Varicosities are packed with small clear vesicles and lie at the surface of nerve bundles. Absence of strong, constant patterns indicating specialized contacts of the nerve terminals is a feature of these nerves at all ages. Some varicosities are closest to interstitial cells; more commonly they are close to muscle cells at sites that strongly suggest a neuro-muscular junction. The additional possibility that some varicosities are part of afferent fibres is discussed. The innervation is well developed at birth and the highest density of innervation is found around day 4 when 4% of the taenia consists of nervous tissue. The innervation of immature taenia is characterized by close juxtaposition of axons and muscle cells. Axon profiles packed with vesicles, varicosities and presumptive neuro-muscular junctions are present at birth. The extent of Schwann cells in intramuscular nerves is markedly less than in adults, and virtually all the axons have maximal membrane-to-membrane contact with other axons. In taenia of aged guinea-pigs, the density of innervation is reduced. There is no actual loss of nerve tissue; the total amount of nerve tissue is greater than in young adults, and the apparent reduction reflects a more intense growth of muscle cells. The Schwann cell component becomes more conspicuous than in young adults and there is a greater number of axons fully wrapped by a Schwann cell. Presumptive neuro-muscular junctions are common and probably commoner than in young adults. Growth of muscle cells, changes in their cytological features and in the stroma occur throughout life, including old age. Nerves too continue to grow and undergo structural changes in pattern of distribution, relation with Schwann cells and effector cells.

Actin Cytoskeleton↗
PubMed1970

The effects of beta adrenoceptor blocking agents on the membrane potential and spike generation in the smooth muscle of guinea-pig taenia coli.

1. The measurement of changes in spike generation and membrane resistance in the guinea-pig taenia coli, using the sucrose gap extracellular recording method, has been shown to be a useful way to demonstrate the intrinsic sympathomimetic activity of the beta adrenoceptor blocking agents.2. Pronethalol, INPEA, MJ 1999, MJ 1998 and dichloroisoprenaline abolish the spontaneous spike discharge and produce a hyperpolarization of the cell membrane. These sympathomimetic effects were blocked by a mixture of alpha (phentolamine) and beta (propranolol) adrenoceptor blocking agents.3. Propranolol reduced the frequency of the spontaneous spike potentials but did not raise the resting membrane potential of the taenia coli.4. When the metabolism of the taenia coli was depressed, all the beta adrenoceptor blocking agents produced a depolarization of the cell membrane and sometimes initiated spike potential activity. The depolarization of the cell membrane was antagonized by superfusing the taenia coli with Krebs solution containing phentolamine. The effects of the beta adrenoceptor blocking agents were not antagonized by the presence of atropine.5. Experiments performed on the reserpinized taenia coli preparation show that depletion of the stores of catecholamines did not modify the sympathomimetic actions of the beta adrenoceptor blocking agents on the normal or metabolically depressed taenia coli preparation. The sympathomimetic action of the beta blocking agents does not appear to be mediated through the release of catecholamines within the taenia coli.

Action Potentials↗
PubMed1984

Tension maintenance, calcium content and energy production of the taenia of the guinea-pig caecum under hypoxia.

When potassium (45.4 mM) was applied to isolated taenia of guinea-pig caecum, the muscle developed a rapid phasic and sustained tonic tension during aerobic conditions bubbled with 95% O2:5% CO2. Under hypoxic conditions bubbled with 95% N2:5% CO2, the taenia lost its ability to respond to high potassium with sustained tonic contraction, although it still showed rapid phasic contraction. Raising the glucose concentration from 5.5 to 55.5 mM in the presence of high potassium during hypoxia caused development of a sustained contraction which was 50% that of the muscle in aerobic conditions. In the presence of high potassium, the ATP content of the taenia decreased in hypoxia, but increased with increasing glucose concentration. When the taenia was exposed to hypoxic conditions, the amount of lactate released from the muscle increased. Raising the glucose concentration caused a further increase in lactate release in the presence of high potassium under hypoxia. Good correlations (gamma greater than 0.9) were observed between tension development, the ATP content and lactate release of the taenia in the presence of high potassium under hypoxia when the glucose concentration was varied between 5.5 and 55.5 mM. The total calcium content was increased by the presence of high potassium under aerobic conditions and the increase was abolished when the muscle was exposed to hypoxic conditions. Under hypoxia the total calcium content was not increased by raising the glucose concentration in the presence of high potassium. The cellular calcium content of the taenia, determined by the lanthanum method, was increased in the presence of high potassium under aerobic and hypoxic conditions, but the content was smaller in hypoxic conditions than in aerobic conditions. Under hypoxic conditions, raising the glucose concentration in the presence of high potassium did not affect the cellular calcium content. These results suggest that under hypoxic conditions the potassium-induced sustained contraction of the taenia is increased by raising the glucose concentration owing to increased ATP production through the glycolytic pathway, but not through mechanisms increasing the intracellular Ca concentration.

Adenosine Triphosphate↗
PubMed2000

Functional assessment of beta adrenoceptor subtypes in human colonic circular and longitudinal (taenia coli) smooth muscle.

BACKGROUND AND AIMS: The subtype and species related heterogeneity of beta adrenoceptors prompted a functional reappraisal of these molecular targets of motility inhibition in the human colon. METHODS: Relaxation of muscle strips was measured in vitro. RESULTS: The following agonists had decreasing relaxing potency (effective concentration range 10(-8)-10(-4) mol/l): (-)isoprenaline (non-selective), terbutaline (beta(2) selective), CGP 12177 (beta(3) selective, also beta(1), beta(2) antagonist), and SR 58611A (beta(3) selective). Isoprenaline and terbutaline were more potent on circular than taenia strips; CGP 12177 and SR 58611A weakly and partially relaxed taenia but had little effect on circular strips. The potency of isoprenaline on circular strips was greatly reduced by the beta(1) selective antagonist CGP 20712 (10(-7) mol/l), and less so by ICI 118551 (10(-7) mol/l, beta(2) selective). CGP 20712 and ICI 118551 together (both 3 x 10(-6) mol/l) had no effect on taenia relaxation by SR 58611A and rendered isoprenaline and terbutaline virtually inactive on circular strips, although not on taenia, which was relaxed at higher than control concentrations and maximally by isoprenaline. Propranolol, a beta(1), beta(2) non-selective antagonist, at high concentrations (10(-5) mol/l) prevented taenia relaxation by CGP 12177 and SR 58611A; its quantitative antagonism of isoprenaline (in common with that of CGP 12177 used as an antagonist) was competitive in circular strips but not on taenia. CONCLUSIONS: beta(1), beta(2), and beta(3) adrenoceptors are functionally detectable in the human colon; agonist stimulation of any one type relaxed taenia but only isoprenaline was fully effective at the beta(3) subtype.

Adrenergic beta-Agonists↗
PubMed1983

The actions of sodium nitroprusside and diltiazem on calcium-, potassium- and histamine-induced contractile responses in isolated rabbit basilar artery, aorta, taenia coli and tracheal smooth muscle.

The effects of sodium nitroprusside (NaNP) and diltiazem on CaCl2-,KCl- and histamine-induced contractile responses were studied in isolated rabbit basilar artery, aorta, taenia coli and trachea. NaNP reduced CaCl2-induced maximal contractions in basilar artery and aorta, but little affected those in taenia coli and trachea. NaNP reduced histamine-induced maximal contraction markedly in aorta but slightly in basilar artery and taenia coli. The reduction in aorta was reversed by increasing CaCl2 contraction in bathing medium. NaNP inhibited histamine-induced contractions of basilar artery, aorta and taenia coli in Ca-free medium. Diltiazem reduced CaCl2-induced maximal contractions in basilar artery and aorta, whilst it caused a parallel shift of concentration-response curves for CaCl2 to the right in taenia coli and trachea. diltiazem reduced histamine-induced maximal contractions in basilar artery and taenia coli. These reductions were reversed by increasing CaCl2 concentration in bathing medium. Diltiazem strongly inhibited histamine-induced contraction of taenia coli in Ca-free medium. The effects of NaNP and diltiazem on KCl-induced contractions both in normal (Ca; 2.5 mM) and in high Ca (Ca; 12.5 mM) media were also studied. From the results obtained in this study, the actions of NaNP and diltiazem were considered to vary with the type of smooth muscle or the condition eliciting contraction. Their possible mechanisms were discussed in this paper.

Animals↗
PubMed1975

[Physiological role of prostaglandins in adrenergic and non-adrenergic inhibitory neurotransmission in guinea pig taenia coli].

Prostaglandin (PG) E1, PGE2 and PGF2alpha and their biosynthesis inhibitor, indomethacin, were tested for their effects on the inhibitory responses of taenia induced by electrical stimulation of adrenergic and/or non-adrenergic inhibitory nerves in the perivascular nerve-taenia preparation isolated from guinea-pig caecum. The response to adrenergic nerve stimulation was considerably reduced by PGE1 and PGE2, while it was little affected by PGF2alpha. Although PGE1 and PGE2 produced contraction of taenia, it may be possible to dismiss from consideration their action of contraction of taenia in accounting for their inhibitory effect on the response to nerve stimulation since the following observations were made, 1) when the taenia were contracted by histamine, the response to adrenergic nerve stimulation was not reduced and 2) in the presence of polyphloretin phosphate, PGE1 and PGE2 did not contract taenia but reduced the response to adrenergic nerve stimulation. In the presence of indomethacin, the response to adrenergic nerve stimulation was increased greatly. On the contrary, the inhibitory response to non-adrenergic inhibitory nerve stimulation was not affected by application of PGE1, PGE2, PGF2alpha and indomethacin. These results suggest that endogenous PG of E series in guinea-pig taenia may play a role in modulating adrenergic neurotransmission. Attempts to demonstrate that PG could operate on a non-adrenergic inhibitory neurotransmission by a negative feedback mechanism were without success.

Animals↗
PubMed1996

Evaluation of P2-purinoceptor antagonists at two relaxation-mediating P2-purinoceptors in guinea-pig taenia coli.

The guinea-pig taenia coli possesses two relaxation-mediating receptors for nucleotides: a prototypic P2Y-purinoceptor, which is activated by adenosine 5'-O-(2-thio-diphosphate) (ADP beta S), and a separate receptor for alpha, beta-methylene ATP (alpha,beta-MeATP). Effects of several as yet incompletely characterized P2-purinoceptor antagonists at these receptors were examined. The concentration-relaxation curve of ADP beta S was shifted to the right by reactive blue 2, suramin, 8-(3,5-dinitro-phenylenecarbonylimino)-1,3,5-naphthalenetrisulp honic acid (XAMR0721; at 1000 microM only), pyridoxalphosphate-6-azophenyl-2',5'-disulphonic acid (iso-PPADS), pyridoxal 5-phosphate, trypan blue and Evans blue (at 320 microM only). Schild plots for the antagonism of reactive blue 2, suramin, iso-PPADS and pyridoxal 5-phosphate against ADP beta S had slopes < 1. The concentration-relaxation curve of alpha,beta-MeATP was shifted to the right by reactive blue 2, suramin, XAMR0721, iso-PPADS, pyridoxal 5-phosphate and trypan blue but not by Evans blue (320 microM). Schild plots for the antagonism of suramin, XAMR0721 and iso-PPADS against alpha,beta-MeATP had slopes > 1. Only XAMR0721 differed clearly in potency against the two nucleotides: it was considerably more potent against alpha,beta-MeATP than against ADP beta S. 2-Methylthio ATP (MeSATP; 1 microM) and ATP (100 microM) were degraded by pieces of taenia coli. All antagonists except trypan blue attenuated the degradation of either or one of the two nucleotides. The selective effect of XAMR0721 against alpha,beta-MeATP confirms the existence of two relaxation-mediating P2-purinoceptors in guinea-pig taenia coli. Comparison of the apparent affinities of the antagonists for the two taenia coli receptors with affinities for the P2X-purinoceptor of the rat vas deferens shows that reactive blue 2, suramin, iso-PPADS, pyridoxal 5-phosphate and trypan blue have little selectivity for any of the three receptors. XAMR0721, which has been shown to possess relatively high affinity for the P2Y-purinoceptor in turkey erythrocytes, was very weak at the P2Y-receptor of the taenia, thus supporting the existence of pharmacologic P2Y-receptor subtypes. Evans blue, with little effect in the taenia coli but a marked effect in the rat vas defrens, is the most selective P2X- (versus P2Y-) purinoceptor antagonists presently known, although its effect on the degradation of nucleotides must be kept in mind.

Adrenergic alpha-Agonists↗
PubMed1986

Effects of the calcium channel facilitator, CGP 28,392, on different modes of contraction in smooth muscle of rabbit and rat aortae and guinea-pig taenia caeci.

Effects of a Ca2+ channel facilitator, CGP 28,392, on smooth muscle contractions were examined in order to delineate characteristics of Ca2+ channels in rabbit and rat aortae and guinea-pig taenia caeci. Application of increasing concentrations of KCl induced contractile responses in these smooth muscles and CGP 28,392 shifted the concentration-response curve for KCl to the left. The maximum response was also increased in rat aorta and guinea-pig taenia. CGP 28,392 also shifted the concentration-response curves for noradrenaline in rat aorta and for histamine in taenia to the left and increased the maximum response in rat aorta. However, the corresponding curve for noradrenaline in rabbit aorta was not affected by CGP 28,392. The sustained contractions induced by KCl were inhibited by cumulative application of verapamil in these smooth muscles. Pretreatment of the muscle with CGP 28,392 decreased the inhibitory effect of verapamil. The noradrenaline-induced contraction in rat aorta and the histamine-induced contraction in taenia were also inhibited by verapamil, and CGP 28,392 antagonized the effect of verapamil. The noradrenaline-induced contraction in rabbit aorta was only slightly inhibited by verapamil, and CGP 28,392 did not modify the effect of verapamil. In these smooth muscles, cumulative application of Ca2+ to the Ca2+-depleted, KCl-treated muscle induced contraction, and the concentration-response curve for Ca2+ was shifted to the left by CGP 28,392 and to the right by verapamil. The concentration-response curves for Ca2+ in Ca2+-depleted, noradrenaline-treated rabbit and rat aortae and in Ca2+-depleted, histamine-treated taenia were also shifted to the left by CGP 28,392 and to the right by verapamil. In some contractions, CGP 28,392 increased and verapamil decreased the maximum responses. CGP 28,392 antagonized the inhibitory effect of verapamil. 5 These results suggest that the Ca2 channel facilitator, CGP 28,392, has a relatively selective activating effect on voltage-dependent Ca2+ channels in rabbit aorta. However, it also activates receptor-linked Ca2+ channels in rabbit aorta when Ca2+ concentrations are low. In rat aorta and guinea-pig taenia this facilitator activates both types of Ca2+ channels.

Animals↗
PubMed1992

Activation of P1- and P2Y-purinoceptors by ADP-ribose in the guinea-pig taenia coli, but not of P2X-purinoceptors in the vas deferens.

1. The activity of adenosine 5'-diphosphoribose (ADP-ribose), a ribosylated purine nucleotide, was investigated on the carbachol-contracted taenia coli, a tissue possessing P1- (A2) and P2Y-purinoceptors and on the guinea-pig vas deferens which possesses P2X-purinoceptors. 2. In the vas deferens, where ATP (1 microM-1 mM) produced concentration-dependent contractions, ADP-ribose was without effect at concentrations up to 1 mM. 3. In the taenia coli, ADP-ribose (0.1 microM-1 mM) produced concentration-dependent relaxations with a potency similar to that of adenosine, but less than that of ATP. The pD2 values for ADP-ribose, adenosine and ATP were 4.5 +/- 0.07 (27), 4.4 +/- 0.10 (9) and 5.5 +/- 0.14 (21), respectively. The time-course of the relaxations elicited by ADP-ribose was found to be significantly longer than that for ATP and significantly shorter than that for adenosine. 4. The P1-purinoceptor antagonist, 8-phenyltheophylline (5 microM), produced parallel rightward shifts in the concentration-response curves of the relaxations of the taenia coli elicited by ADP-ribose and adenosine but not ATP. 5. Dipyridamole (0.3 microM), a purine nucleoside uptake inhibitor, potentiated the responses to adenosine and ADP-ribose in the taenia coli. These potentiations were sensitive to 8-phenyltheophylline (5 microM). 6. Reactive blue 2, a P2Y-purinoceptor antagonist, antagonized the inhibitory responses of ADP-ribose and ATP in the taenia coli, without significantly altering the inhibitory responses of either adenosine or noradrenaline.7. In the presence of the potassium channel blocker, apamin (0.3 microM), the inhibitory responses of ADP-ribose were severely attenuated, and the inhibitory responses of ATP in the taenia coli were converted to transient contractions. Further addition of 8-PT blocked the residual responses of ADPribose.8. The P2-purinoceptor antagonist, suramin (500 microM), antagonized responses to ATP and ADP-ribose,but not adenosine. Further addition of 8-PT antagonized the residual responses to ADP-ribose, but not to ATP.9. It is concluded that ADP-ribose has a mixed pharmacological profile, evoking both PI (A2)-purinoceptor-mediated responses and P2Y-purinoceptor-mediated responses, while being inert at P2Xpurinoceptors.It is suggested that ADP-ribose may provide a useful starting point for the generation of structural analogues which have specific activity at the P2Y-purinoceptor.

Adenosine Diphosphate Ribose↗
PubMed1985

Increase in membrane permeability in the absence of Ca and Mg in the smooth muscle of guinea-pig taenia coli.

In Ca-deficient smooth muscle of guinea-pig taenia coli, repeated application of high-K solution (45.4 mM) containing Ca induced contractions of similar shape and magnitude. In muscle treated by a Ca- and Mg-deficient solution, however, addition of Ca and K either did not induce contraction or induced only a delayed contraction. Ouabain (1 X 10(-3) M) also inhibited Ca- and K-induced contraction. Na content of taenia coli smooth muscle increased and K content decreased during incubation in Ca- and Mg-deficient solution. Ouabain produced similar, but smaller, changes in Na and K contents. Contractility of Ca- and Mg-deficient taenia partially recovered if the muscle was treated with Na-deficient solution which resulted in a large decrease in Na content. Similar treatment produced only a small decrease in Na content in ouabain-treated taenia, and contractility did not recover in these muscles. Application of hyperosmotic NaCl (160 mM) decreased tissue weight in both control and ouabain-treated taenia. In muscle treated with Ca- and Mg-deficient solution, however, hyperosmotic NaCl application had little effect on tissue weight. Following pretreatment of muscle with Ca- and Mg-deficient solution (containing 2 mM EDTA) for 2 hr, graded contractions were induced by cumulative application of Ca between 10(-7) to 10(-6) M in the presence of Mg and ATP. It is concluded that Ca- and Mg-deficient solution increases membrane permeability and also abolishes transmembrane gradients of Na and K in guinea pig taenia coli.

Animals↗
PubMed1987

Inhibition by amiloride of contractile elements in smooth muscle of guinea pig taenia cecum and chicken gizzard.

The relaxant action of amiloride was investigated in the smooth muscles of guinea pig taenia ceci and chicken gizzard. Amiloride inhibited the contractions induced by high K+ (45.4 mM) and carbachol (10 microM) in the taenia with the concentrations needed to induce 50% inhibition (IC50) of approximately 41 microM. A prolonged incubation period (greater than 1 hr) was necessary to obtain the full inhibition of these contractions. The taenia gradually accumulated amiloride and the tissue/medium ratio exceeded 2.0 after a 120-min incubation period. Amiloride had no effect on the high K+-stimulated 45Ca++ uptake or the ATP content of the taenia. Amiloride inhibited the Ca++-induced contraction of the saponin-treated taenia with an IC50 of 186 microM. Amiloride (10-1000 microM) also inhibited superprecipitation and Mg++-adenosine triphosphatase activity of the gizzard native actomyosin as well as the phosphorylation of myosin light chain. The inhibition of the phosphorylation was antagonized competitively by ATP. Amiloride (1 mM) had no effect on the dephosphorylation of myosin light chain upon removal of Ca++ from reaction medium. Amiloride, at concentrations up to 1 mM, had not effect on calmodulin activity as monitored by the Ca++-calmodulin-activated erythrocyte membrane (Ca++ + Mg++)-adenosine triphosphatase and phosphodiesterase activities. In contrast to this, trifluoperazine inhibited the calmodulin activity at the concentration needed to inhibit the Ca++-induced contraction of the permeabilized taenia and the superprecipitation and the phosphorylation of myosin light chain of gizzard. We conclude that amiloride, unlike trifluoperazine, may inhibit directly the myosin light chain kinase activity to induce muscle relaxation.

Actomyosin↗
PubMed1981

Evidence for and significance of the projection of VIP neurons from the myenteric plexus to the taenia coli in the guinea pig.

Immunohistochemical studies of the distribution of vasoactive intestinal polypeptide were made in the cecum from normal guinea pigs and from guinea pigs after lesions of the cecal wall had been made. These experiments were designed to determine the origin of the vasoactive intestinal polypeptide axons which supply the taenia of the cecum in order to ascertain whether the projections of the vasoactive intestinal polypeptide neurons were consistent with VIP being contained in enteric inhibitory neurons. Vasoactive intestinal peptide was found in nerve cell bodies of both the myenteric and submucous taenia and the myenteric plexus the vasoactive intestinal polypeptide fibers in the taenia disappeared, but there was no effect on these fibers if the taenia was separated from the submucous plexus or surrounding muscle while leaving connections with the myenteric plexus intact. Retrograde degenerative signs were seen in VIP fibers and nerve cell bodies of the myenteric plexus after removal of the taenia. In conclusion, VIP is contained in neurons that have the same projections as the enteric inhibitory neurons from the myenteric plexus to the taenia of the cecum.

Animals↗
PubMed1995

Histochemical, pharmacological, biochemical and chromatographic evidence that pituitary adenylyl cyclase activating peptide is involved in inhibitory neurotransmission in the taenia of the guinea-pig caecum.

The possibility that pituitary adenylyl cyclase-activating peptide (PACAP) is an inhibitory neurotransmitter has been investigated in the taenia of the guinea-pig caecum. The action of PACAP on muscle contractility and its ability to alter levels of adenosine-3':5'-cyclic monophosphate (cyclic AMP) and guanosine-3':5'-cyclic monophosphate (cyclic GMP) were investigated. PACAP-1-27 was an effective agonist, giving relaxations comparable in magnitude to isoproterenol; its EC50 was 3.4 x 10(-7) M. PACAP (10(-6) M) caused an almost two-fold increase in cyclic AMP levels; but the level of cyclic GMP was not affected. The relaxation caused by PACAP was slow in onset, with a latency of 5.8 +/- 0.8 s and reached a maximum at 9.1 +/- 1.1 s after onset. The relaxation was significantly reduced by apamin (10(-6) M) and suramin (10(-4) M) but was not reduced by tetrodotoxin (10(-7) M). Relaxation of the taenia coli caused by electrical stimulation of the inhibitory nerves was greatly reduced by apamin but only slightly reduced by suramin. PACAP-like immunoreactivity (-IR) was localised immunohistochemically in varicose nerve fibres within the taenia coli and in the underlying myenteric plexus and circular muscle. Approx. 50% of vasoactive intestinal peptide (VIP)-IR nerve fibres in the taenia also had immunoreactivity for PACAP; conversely, almost all PACAP-IR fibres were immunoreactive for VIP. PACAP-IR and substance P (SP)-IR were generally in separate fibres; only about 5% of SP-IR fibres were PACAP-IR. Radioimmunoassay revealed tissue concentrations of PACAP-1-27 and PACAP-1-38 of 1.0 +/- 0.1 and 2.1 +/- 0.3 (SEM) pmol/g wet weight of tissue, respectively. Material with PACAP-1-27 immunoreactivity co-eluted with authentic PACAP-1-27 on gel filtration chromatography, and PACAP-1-38 immunoreactivity also co-eluted with the authentic peptide. This study provides structural, chemical and pharmacological evidence that PACAP could be involved in inhibitory neurotransmission to the taenia coli of the guinea-pig caecum.

Animals↗
PubMed2004

Taenia antigens detection in the cerebrospinal fluid of patients with neurocysticercosis and its relationship with clinical activity of the disease.

OBJECTIVE: (1) To determine the concentration of Taenia antigens in the cerebrospinal fluid (CSF) of patients with neurocysticercosis (NC); (2) to establish its relationship with clinical activity of the disease and with classical variables of CSF. METHOD: A CSF examination was performed in one sample from 36 patients with definitive diagnosis of NC, including: quantitative and cytomorphological study, biochemical tests, immunological reactions for cysticercosis and Taenia antigens. The antibodies for antigens detection were obtained from the larval form of Taenia crassiceps, ORF strain. After intraperitoneal passage through female mice, a group of rabbits was immunized with vesicular fluid antigens. RESULTS: The Taenia antigen was detected in CSF from 17 patients (47.2%), especially in those patients with epileptic symptoms in the last 12 months. CONCLUSION: Taenia antigens presence in CSF have significant relationship with clinically active forms of NC, being a more sensitive marker than the classic eosinophil presence.

Adult↗
PubMed1993

Morphologic descriptions of Taenia asiatica sp. n.

Among taeniid tapeworms infecting humans through pork or beef, Taenia solium Linnaeus 1758 and Taenia saginata Goeze 1782 have already been known. Based on the morphologic characteristics of adult and metacestodes of Asian Taenia saginata, the third kind of human taeniid tapeworm known to distribute in Asian countries, a new species name of Taenia asiatica is proposed. In addition to the known biology in their intermediate hosts, T. asiatica was different morphologically from Taenia saginata Goeze 1782 in having the unarmed rostellum on the scolex of adult, the large number of 'uterine twigs' and the existence of 'posterior protuberance'. These structures in the gravid proglottids were used as taxonomic keys in taeniid tapeworms for the first time. T. asiatica metacestode (Cysticercus viscerotropica) was different morphologically from T. saginata metacestode (Cysticercus bovis) in having wartlike formations on the external surface of the bladder wall.

Adult↗
PubMed1991

Asian Taenia saginata: species or strain?

Asian Taenia has a special epidemiological pattern. Many people eat raw and/or undercooked pork and pig viscera more often than that of cattle and acquire a T. saginata-like tapeworm infection. The pig has been found to be the most favorable laboratory intermediate host for four geographical strains of Asian Taenia. Numerous pinpoint cysticerci have been found in naturally infected livers of one wild boar and six domestic pigs in Taiwan. It is likely that pigs are the natural intermediate host of Asian Taenia in endemic areas other than Taiwan. Moreover, the cysticerci of Asian Taenia are only found in the livers of the infected animals and have similar morphological characteristics, which are distinguishable from the cysticerci of T. saginata and T. solium. These cysticerci are small in size and armed with two rows of rudimentary hooklets and can develop to maturity in as short a period as 4 weeks. It is possible that Asian Taenia is a different species or at least a different strain.

Animals↗
PubMed1988

Role of sodium ions in angiotensin tachyphylaxis in the guinea-pig ileum and taenia coli.

We have examined the responsiveness of the guinea-pig ileum and taenia coli to angiotensin (ANG) analogues that were previously shown to be either able ([1-sarcosine]-ANG, Sar1-ANG) or unable ([2-lysine]-ANG, Lys2-ANG) to induce tachyphylaxis in the ileum. The taenia coli, in which tachyphylaxis had not been previously shown to occur, was strongly tachyphylactic to Sar1-ANG, but not to Lys2-ANG. The contractile responses of the ileum, as well as the contractile and electrical (sucrose-gap) events in the taenia coli, in response to the two ANG analogues, were used to investigate the tachyphylactic phenomenon and the role of Na+ in the manifestation. Relaxation of the ileum and repolarizations of the taenia coli were faster after treatment with Lys2-ANG than after Sar1-ANG. In the tachyphylactic state, relaxation and repolarization after Sar1-ANG became as fast as after Lys2-ANG. In "low-Na+" (80 mmol/l) medium, as well as in ouabain-treated preparations, the responses of the ileum to ANG analogues were similar to those of tissues in the tachyphylactic state. Addition of Ca2+ to taenia coli preparations previously treated with the two ANG analogues in Ca2+-free medium, caused contractile and electrical responses only in the case of Sar1-ANG. It is proposed that ANG tachyphylaxis is due to changes at the level of the receptor causing increased Na+ permeability which leads to a decreased Na+ gradient across the cell membrane.

Angiotensin I↗