K transport and mechanical responses of isolated longitudinal smooth muscle from guinea pig ileum

1961 ◽  
Vol 200 (4) ◽  
pp. 789-793 ◽  
Author(s):  
George B. Weiss ◽  
Robert E. Coalson ◽  
Leon Hurwitz
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Contractile Response ◽  
Muscle Tone ◽  
Muscle Layer ◽  
Smooth Muscle Contraction ◽  
Potassium Ion ◽  
Guinea Pig Ileum ◽  
Potassium Efflux ◽  
Longitudinal Smooth Muscle

The longitudinal smooth muscle layer of the guinea pig ileum was isolated in order to investigate its contractile responses and unidirectional K42 fluxes. Pilocarpine (7.5 x 10–6 m), acetylcholine (6.6 x 10–6 m), and a modified Tyrode's solution in which potassium ion was substituted for almost all the sodium ion were employed as excitatory agents. Cocaine (8.5 x 10–4 m) and a calcium-free Tyrode's solution served as inhibitory agents. Smooth muscle tone and potassium efflux of this relatively pure tissue were both increased by all three excitatory substances. Moreover, acetylcholine and pilocarpine produced a decrease in the influx of potassium ion. Bathing the tissue in a calcium-free medium for 1 hour before introducing pilocarpine to the muscle bath eliminated the contractile response that this drug ordinarily produces, but did not diminish appreciably the increase in K42 efflux. These observations are qualitatively similar to results previously obtained in analogous experiments on isolated whole ileum. In addition, cocaine (8.5 x 10–4 m) was found to block the contractile response and about three-quarters of the enhanced K42 efflux elicited by the isotonic potassium solution. It is presumed that cocaine acting at the membrane impedes ion fluxes important for smooth muscle contraction.

Smooth muscle contraction in presence of an inhibitor of K efflux

1964 ◽  
Vol 206 (5) ◽  
pp. 1021-1024 ◽  
Author(s):  
Allan D. Bass ◽  
Leon Hurwitz ◽  
Bolton Smith
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Smooth Muscle Contraction ◽  
Potassium Ion ◽  
Guinea Pig Ileum ◽  
Pronounced Change ◽  
Potassium Efflux ◽  
Longitudinal Smooth Muscle ◽  
Desoxycorticosterone Acetate ◽  
Smooth Muscle Contractions

Contractions of the isolated longitudinal smooth muscle from guinea pig ileum produced by pilocarpine are regularly accompanied by increases in the efflux of potassium ion. A concentration of 7.4 x 10–6 m pilocarpine produced a maximum smooth muscle contraction and an increase in potassium efflux which averaged 157% above that of unexcited fibers. In the presence of appropriate concentrations of the inhibitor (desoxycorticosterone acetate) pilocarpine evoked small to negligible increases in potassium efflux, whereas the smooth muscle contractions elicited were about 81% of the control. These data show that pilocarpine can produce a near maximal smooth muscle contraction in the absence of any pronounced change in outward flux of potassium ion.

Amphibian toxins from the skin of Bufo regularis have inhibitory effect on electrically invoked contractile response and bimodal effects on tone of longitudinal muscle of guinea pig ileum

2019 ◽  
Vol 34 (1) ◽  
pp. 9-22
Author(s):  
Tesfaye Tolessa
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
High Performance ◽  
Longitudinal Muscle ◽  
Contractile Response ◽  
Inhibitory Effect ◽  
Muscle Strip ◽  
Organ Bath ◽  
Guinea Pig Ileum ◽  
Longitudinal Smooth Muscle

The skins of some amphibians contain potentially bioactive principles that may have pharmaceutical, medicinal, toxicological or chemical importance. In addition, such active principles can be used as tools in biomedical research. The present study aims at isolating and purifying bioactive principles from the skin of Bufo regularis and studying their effect on isolated longitudinal smooth muscle strip of guinea pig ileum. High performance liquid chromatography (HPLC) was used to isolate toad toxins. The effects of crude, semi-purified and purified extracts were tested on longitudinal smooth muscle of guinea pig ileum using organ bath method. Effect of the toxins was studied on electrically-induced contractile response and the basal tone of the longitudinal muscle strip. HPLC purification resulted in four different bioactive components with a λmax UV absorbance pattern of around 295 nm. When tested on guinea pig ileum they had persistent inhibitory effect on the electrically-induced contractile responses. The pattern of effect was initial excitatory followed by long lasting inhibitory effect on tone of longitudinal muscle. The HPLC eluate at 79th min in methanol preparative run corresponding to the eluate at 40th min in the acetonitrile run had the maximum bioactivity. Hence, it was concluded that the skin of B. regularis contains four different components which vary in their potency on isolated smooth muscle strip of guinea pig ileum.Keywords: Bufo regularis, organ bath, longitudinal muscle of ileum, toad toxin, electrical field stimulation

Dissociation of contraction and potassium efflux in smooth muscle

1960 ◽  
Vol 199 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Leon Hurwitz ◽  
Betty Tinsley ◽  
Frank Battle
Keyword(s):  
Smooth Muscle ◽  
Contractile Response ◽  
Muscle Tone ◽  
Potassium Transport ◽  
Free Medium ◽  
Additional Increase ◽  
Potassium Efflux ◽  
Smooth Muscle Tone ◽  
Longitudinal Smooth Muscle ◽  
Sudden Rise

Normally, a pilocarpine induced contraction of the isolated guinea pig ileum is associated with a change in potassium transport across cell membranes. Bathing the tissue in a Ca-free medium will effect a dissociation between the contractile response and the potassium efflux. The replacement of Tyrode's solution by a Ca-free medium elicits a slight increase in smooth muscle tone followed by a return to a state of relaxation. Within an hour the contractile response to pilocarpine becomes negligible. This lack of response to pilocarpine applies to circular as well as longitudinal smooth muscle. In contrast to the changes which occur in muscle tone the efflux of potassium, following withdrawal of Ca ion, undergoes a sudden rise and remains above normal. The administration of pilocarpine, after the tissue has been bathed in the Ca-free medium for 1 or 2 hours, will still evoke a moderate additional increase in potassium efflux. Replacement of Ca ion with an equimolar quantity of Mg ion causes the contractile response to pilocarpine to disappear sooner than it would have in a simple calcium-free medium. Here, too, the potassium efflux of the tissue rises and after 1 hour responds to pilocarpine with a further increase. Thus, pilocarpine can modify potassium transport in the isolated ileum regardless of its effect on smooth muscle tone.

PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

2007 ◽  
Vol 292 (3) ◽  
pp. G887-G898 ◽  
Author(s):  
Daniel P. Poole ◽  
John B. Furness
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscles ◽  
Specific Inhibitor ◽  
Smooth Muscle Contraction ◽  
Enteric Neurons ◽  
Guinea Pig Ileum ◽  
Tonic Component ◽  
Gastrointestinal Smooth Muscle ◽  
Immunohistochemical Evidence

PKC is involved in mediating the tonic component of gastrointestinal smooth muscle contraction in response to stimulation by agonists for G protein-coupled receptors. Here, we present pharmacological and immunohistochemical evidence indicating that a member of the novel PKC isoforms, PKC-δ, is involved in maintaining muscarinic receptor-coupled tonic contractions of the guinea pig ileum. The tonic component of carbachol-evoked contractions was enhanced by an activator of conventional and novel PKCs, phorbol 12,13-dibutyrate (PDBu; 200 nM or 1 μM), and by an activator of novel PKCs, ingenol 3,20-dibenzoate (IDB; 100 or 500 nM). Enhancement was unaffected by concentrations of bisindolylmaleimide I (BIM-I; 22 nM) that block conventional PKCs or by a PKC-ε-specific inhibitor peptide but was attenuated by higher doses of BIM-I (2.2 μM). Relevant proteins were localized at a cellular and subcellular level using confocal analysis. Immunohistochemical staining of the ileum showed that PKC-δ was exclusively expressed in smooth muscles distributed throughout the layers of the gut wall. PKC-ε immunoreactivity was prominent in enteric neurons but was largely absent from smooth muscle of the muscularis externa. Treatment with PDBu, IDB, or carbachol resulted in a time- and concentration-dependent translocation of PKC-δ from the cytoplasm to filamentous structures within smooth muscle cells. These were parallel to, but distinct from, actin filaments. The translocation of PKC-δ in response to carbachol was significantly reduced by scopolamine or calphostin C. The present study indicates that the tonic carbachol-induced contraction of the guinea pig ileum is mediated through a novel PKC, probably PKC-δ.

scholarly journals Relationship between stimulated phosphatidic acid production and inositol lipid hydrolysis in intestinal longitudinal smooth muscle from guinea pig

1987 ◽  
Vol 244 (3) ◽  
pp. 763-768 ◽  
Author(s):  
R S E Mallows ◽  
T B Bolton
Keyword(s):  
Smooth Muscle ◽  
Small Intestine ◽  
Substance P ◽  
Guinea Pig ◽  
Phosphatidic Acid ◽  
Inositol Phosphates ◽  
Muscle Layer ◽  
Phospholipid Hydrolysis ◽  
Longitudinal Smooth Muscle ◽  
Inositol Phospholipid

Accumulation of [32P]phosphatidic acid (PA) and total [3H]inositol phosphates (IPs) was measured in the longitudinal smooth-muscle layer from guinea-pig small intestine. Stimulation with carbachol, histamine and substance P produced increases in accumulation of both [3H]IPs and [32P]PA over the same concentration range. The increase in [32P]PA accumulation in response to carbachol (1 microM-0.1 mM) was inhibited in the presence of atropine (0.5 microM). Buffering the external free [Ca2+] to 10 nM did not prevent the carbachol-stimulated increase in [32P]PA accumulation. Carbachol and Ca2+ appear to act synergistically to increase accumulation of [32P]PA. In contrast, although incubation with noradrenaline also increased accumulation of [3H]IPs, no increase in accumulation of [32P]PA could be detected. These results suggest that an increase in formation of IPs is not necessarily accompanied by an increase in PA formation, and imply the existence of receptor-modulated pathways regulating PA concentrations other than by phospholipase-C-catalysed inositol phospholipid hydrolysis.

Sign in / Sign up

Export Citation Format

Share Document