Ultrastructure, calcium accumulation, and contractile response in smooth muscle

After removing extracellular Ca2+ with [ethylene bis(oxyethylenenitrilo)]tetraacetic acid, we found that the guinea pig vas deferens (VD) was mechanically responsive to electrical stimulation for a significantly greater length of time than was guinea pig taenia coli (TC). An obvious explanation for these findings is that the VD has more intracellular calcium available for contraction than does the TC. To determine if this explanation is plausible, the volume of internal storage structures within the two muscles was compared. It was found that the volumes of potential sequestering structures in the VD and TC are not significantly different. Next, the affinities of the storage structures for calcium were compared. The VD was found to accumulate approximately twice as much 45Ca as did the TC, as determined by 45Ca autoradiography. Calcium-45 was present to a greater extent in association with surface vesicles, sarcoplasmic reticulum (SR), and mitochondria than in the unassociated state within the cytoplasmic matrix. Based on the results of these experiments, we suggest that the VD and the TC of the guinea pig differ in the affinity of their storage sites for calcium.

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Does 5-hydroxytryptamine influence "purinergic" inhibitory neurons in the intestine?

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1979.237.2.e198 ◽

1979 ◽

Vol 237 (2) ◽

pp. E198

Author(s):

D L Vermillion ◽

J P Gillespie ◽

A R Cooke ◽

J D Wood

Keyword(s):

Electrical Stimulation ◽

Guinea Pig ◽

Contractile Response ◽

Circular Muscle ◽

Inhibitory Neurons ◽

Relaxation Response ◽

Taenia Coli ◽

Synaptic Excitation ◽

Small Intestinal ◽

Neurotransmitter Substance

Intrinsic inhibitory neurons to guinea pig taenia coli and small bowel circular muscle were activated by transmural electrical stimulation, and the postinhibitory contractile response of the muscle was utilized to evaluate whether or not the neuronal action of 5-hydroxytryptamine (5HT) was associated with the inhibitory neurons. The postinhibitory contractile responses of the small intestinal circular muscle were unaffected by 5HT. The 5HT antagonist methysergide also did not affect the poststimulus contractile response of the circular muscle. The amplitude and area under the contractile curve of the poststimulus contractile response of the taenia coli were reduced and the amplitude of the relaxation response to electrical stimulation was increased in one-half of the preparations after application of 5HT. Methysergide did not alter the poststimulus contractile response of the taenia coli. 5HT is implicated as a neurotransmitter substance for slow synaptic excitation within the enteric nervous system of the guinea pig small intestine; however, the 5HT synapses do not appear to be present on the "purinergic" inhibitory neurons nor on neurons that synaptically influence the inhibitory neurons.

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Action of Cytochalasin B on the Contraction of Smooth Muscle of Guinea Pig Taenia Coli, Vas Deferens and Rat Uterus

The Tohoku Journal of Experimental Medicine ◽

10.1620/tjem.110.181 ◽

1973 ◽

Vol 110 (2) ◽

pp. 181-189 ◽

Cited By ~ 3

Author(s):

TAKEO MARUYAMA ◽

JUNICHIRO NAGASAWA ◽

TAIZO SUZUKI

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Cytochalasin B ◽

Vas Deferens ◽

Taenia Coli ◽

Rat Uterus

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A STUDY OF NEXUSES IN VISCERAL SMOOTH MUSCLE

The Journal of Cell Biology ◽

10.1083/jcb.41.1.287 ◽

1969 ◽

Vol 41 (1) ◽

pp. 287-297 ◽

Cited By ~ 30

Author(s):

J. L. S. Cobb ◽

Terence Bennett

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Smooth Muscle Cells ◽

Osmium Tetroxide ◽

Vas Deferens ◽

Muscle Cells ◽

Taenia Coli ◽

Muscle Tissues ◽

Fixation Techniques ◽

Visceral Smooth Muscle

Nexuses are described between the smooth muscle cells of the gizzard of the chick and the pigeon, the vas deferens of the mouse and the guinea pig, and the taenia coli of the guinea pig. The nexuses in the gizzard were examined after osmium tetroxide and potassium permanganate had been used as fixatives. Although differences in the dimensions of the unit membranes and the nexuses were noted, the results with the two fixation techniques were complementary. The distribution of nexuses within the smooth muscle tissues examined was uneven. Nexuses were still present in both small and large pieces of tissue incubated in hypertonic solutions at varying temperatures. Other experiments showed that the degree of contraction at the time of fixation did not affect the presence of nexuses in the tissue. These results indicate that nexuses between smooth muscle cells are stable under a variety of conditions.

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Tetrodotoxin-resistant release of ATP from guinea-pig taenia coli and vas deferens during electrical field stimulation in the presence of luciferin-luciferase

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y81-167 ◽

1981 ◽

Vol 59 (10) ◽

pp. 1094-1100 ◽

Cited By ~ 28

Author(s):

Thomas White ◽

Pamela Potter ◽

Catherine Moody ◽

Geoffrey Burnstock

Keyword(s):

Guinea Pig ◽

Action Potentials ◽

Vas Deferens ◽

Contractile Response ◽

Atp Release ◽

Electrical Field Stimulation ◽

Field Stimulation ◽

Taenia Coli ◽

Initial Exposure ◽

Low Tone

Guinea-pig taenia coli was superfused with medium containing luciferin-luciferase at 25 °C in order to directly detect the release of ATP. The resting lone of the tissue increased during the first 2–10 min of superfusion and then fell to a low level where spontaneous activity ceased. Under high tone conditions during the first 2–10 min of exposure to luciferin-luciferase, in the presence of atropine and guanethidine, ATP was released and the taenia coli relaxed when stimulated at 2–4 Hz, 70 V, 0.3-ms pulses for 15 s. Variable and continuous changes of tone made it difficult to test whether relaxation and release of ATP were tetrodotoxin sensitive. Field stimulation of preparations showing low tone after the initial exposure to luciferin-luciferase also resulted in ATP release. The muscle usually contracted during stimulation, even in the presence of atropine. Release was not due to movement of the muscle, since the release preceded the movement of the tissue and contraction with acetylcholine failed to release ATP. Neither release nor the contractile response of the tissue were blocked by tetrodotoxin (3 × 10−6 M), suggesting that under these conditions the release of ATP originated from the muscle or possibly directly from nerve terminals. A qualitatively similar release of ATP was also observed when desheathed guinea-pig vas deferens was field-stimulated electrically in the presence of luciferin-luciferase. Tetrodotoxin did not block ATP from this tissue either, but unlike the taenia coli, it did abolish the contractile response, which was not affected by luciferin-luciferase during the 1st h of exposure. It is concluded that in the presence of luciferin-luciferase the field-stimulation induced release of ATP observed in guinea pig taenia coli or vas deferens was not mediated by propagation of action potentials in nerve.

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