Deficiency of .BETA.-adrenoceptor-mediated relaxation in Suncus trachea.

Nagata, Kôichi; Abe, Kazuho; Wang, Chao-Hsiung; Saito, Hiroshi; Matsuki, Norio

doi:10.1254/jjp.52.115

Cited by 7 publications

(2 citation statements)

References 17 publications

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“…We have shown that (3-adrenoceptor mediated responses in suncus ventricle and trachea are very small in comparison with those in rats or guinea pigs and suggest ed deficient coupling between (3-adrenoceptors and adeny late cyclase (9,11). Characteristics of the guanine nucleo tide binding proteins in suncus tissue may be different from those in other species.…”

Section: Discussionmentioning

confidence: 74%

Adenosine Induces Contractions in Suncus Ileum

Nagata

Saito

Matsuki

1993

Japanese Journal of Pharmacology

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ABSTRACT-Purinoceptor-mediated responses were characterized in the ileum of Suncus murinus. Adenosine as well as adenosine 5 triphosphate (ATP) contracted the ileum in a concentration-dependent manner. Contractile responses to transmural electrical stimulation were attenuated by adenosine only at high concentrations. Theophylline competitively blocked the adenosine-induced contraction. Atropine also inhibited the adenosine-induced contraction but in a non-competitive manner. The ATP-induced contrac tion was not affected by theophylline, atropine or a,13-methylene ATP. Indomethacin shifted the concentra tion-response curves for adenosine and ATP to the right. These results suggest that adenosine elicited con tractions via direct stimulation of postsynaptic PI-purinoceptors and postsynaptic potentiation of the acetylcholine response. Suncus ileum will be a unique model for the analyses of purinoceptor-mediated responses. Keywords:Purinoceptor, Purine nucleotide, Theophylline, Atropine, IndomethacinSuncus murinus (suncus), which belongs to the family Soricidae of the order insectivore, is regarded as the direct ancestor of the primate in the phylogenetic system (1). We have been characterizing the suncus and found that this animal is a good model for studies on nerve growth factor (2), stress (3), emesis (4), motion sickness (5) and lipid metabolism (6, 7). As for the pharmacological properties of their cardiovascular systems, the following unique fea tures were found: norepinephrine decreases the heart rate (8); ~-adrenoceptor-mediated response is deficient in the cardiac muscle (9) and the duration of cardiac action potential is extremely short (10). However, little is known about the pharmacological properties of suncus smooth muscle. In tracheal smooth muscle, the j3-adrenoceptor mediated response is also small (11). Muraki et al. (12) showed that isoproterenol, histamine and neuropeptides cause unique responses of suncus intestine.In the present study, effects of purine derivatives on contraction of suncus ileum were studied for the possible use of the preparation as a new experimental model. The purine derivatives, such as adenosine and adenine nucleo tides, exert several physiological and pharmacological effects on a variety of tissues innervated by the autonomic nervous system (13,14). MATERIALS AND METHODS Recording of mechanical responses of isolated prepara tionsMale adult suncus (50-75 g) were sacrificed, and the in testines were quickly isolated. Since the suncus intestine is short and lacks a cecum, appendix vermiformis and tae nia coli, it is rather difficult to distinguish among the duo denum, jejunum, ileum and colon (15). We regarded the proximal (oral) part of the intestine (of about 3 cm) as the duodenum and the distal (anal) part of 1 cm as the colon. The remainder of the intestine was cut into 3-cm-long pieces and used for experiments as ileal preparations.Each preparation was vertically mounted in a 5 ml-or gan bath containing physiological salt solution of the fol lowing composition: 118.0...

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Section: Discussionmentioning

confidence: 74%

Adenosine Induces Contractions in Suncus Ileum

Nagata

Saito

Matsuki

1993

Japanese Journal of Pharmacology

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“…We have shown previously that ~-adrenoceptor-mediat ed responses in the heart and trachea are very small in sun cus (13,14) and suggested the deficient coupling between f3-adrenoceptors and the adenylate cyclase system. The present study showed that the decrease in blood pressure by ISO is also small in suncus.…”

Section: Discussionmentioning

confidence: 90%

Biochemical and Pharmacological Properties of a Newly Synthesized Proton Pump (H+/K+-ATPase) Inhibitor, TY-11345 in Experimental Animals

Matsuki

Sakuma

Saito

1993

Japanese Journal of Pharmacology

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ABSTRACT-Blood pressure and heart rate and responses to various physiological substances in suncus were characterized and compared with those in mice. The blood pressures of the two species were similar, but the heart rate of suncus (about 400 beat/min) was significantly lower than that of mice. Norepinephrine increased the blood pressure but decreased the heart rate in suncus. The latter was blocked by cervical vagotomy. Sensitivities to acetylcholine and isoproterenol were lower in suncus. These results suggest that regulation of blood pressure and heart rate in suncus is very unique and different from the well-defined system of the rodents.

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Change of intracellular calcium of neural cells induced by extracellular ATP

et al. 1991

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Exposure of various neural cells to ATP increased intracellular Ca*' and the production of inositol trisphosphate. The Cazt responses were ah observed in the absence of extracellular Cat', suggesting that a part of Cat+ mobilization took place from cytosolic storage. Since adenosine had no effect on intracellular Cal* increment, ATP appears to act through a P,-purinergic receptor. Islet-activating protein or pertussis toxin pretreatment hardly influenced the increase in intracellular Ca2+ and inositol trisphosphate production induced by ATP, suggesting that IAP-sensitive GTPbinding proteins do not play a practical role in this reaction.

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Deficiency of .BETA.-adrenoceptor-mediated relaxation in Suncus trachea.

Cited by 7 publications

References 17 publications

Adenosine Induces Contractions in Suncus Ileum

Adenosine Induces Contractions in Suncus Ileum

Biochemical and Pharmacological Properties of a Newly Synthesized Proton Pump (H+/K+-ATPase) Inhibitor, TY-11345 in Experimental Animals

Change of intracellular calcium of neural cells induced by extracellular ATP

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