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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 317 (1981), S. 86-89 
    ISSN: 1432-1912
    Keywords: Glomerular capillary pressure ; Munich-Wistar rat ; Adenosine ; Ureteral obstruction ; Aortic constriction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of acute ureteral obstruction (UO) and reduction of renal artery pressure (AC) on the adenosineinduced renal vasoconstriction was studied in the Munich-Wistar rat. Infusion of adenosine, 0.05 μmol/min · kg body weight, into the thoracic aorta, was associated with a fall of directly measured glomerular capillary pressure (P gc) from 45.2+1.8 to 32.5+1.7 mm Hg, P〈0.001. Elevation of ureter pressure to 39+2 mm Hg abolished the fall of P gc following adenosine infusion, 51.3+1.7 vs. 50.0+1.3 mm Hg, NS. Reduction of renal artery pressure to 70 mm Hg by an aortic clamp above the renal arteries also prevented the fall of P gc due to adenosine, 36.8+0.9 vs. 36.4+1.8 mm Hg, NS. Administration of indometacin (10 mg/kg i.v.) restored the ability of adenosine to reduce P gc in UO from 41.5+1.1 to 25.9+2.6 mm Hg (P〈0.001) and in AC from 34.0+3.4 to 28.2+75.7 mm Hg (P〈0.02). Since previous studies have demonstrated that in UO and AC renal prostaglandin synthesis is enhanced the effects of indometacin suggest that prostaglandins could be antagonistic to the action of adenosine on the kidney. The data show that the renal vasculature becomes insensitive to the vasoconstrictive action of adenosine during elevated ureter pressure and reduced renal artery pressure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 229-236 
    ISSN: 1432-1912
    Keywords: Key words BIMU 8 ; BIMU 1 ; Renzapride ; 5-HT4 receptors ; Acetylcholine release ; Myenteric plexus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of the 5-HT4 receptor agonists BIMU 8, BIMU 1, renzapride and of the 5-HT1p receptor agonist 5-hydroxyindalpine on basal and electrically evoked outflow of tritium were studied in guinea-pig longitudinal muscle myenteric plexus preparations preincubated with [3H]choline. Muscle contractions were recorded simultaneously. BIMU 8 caused a calcium dependent and tetrodotoxin sensitive increase in basal [3H]outflow that was assumed to represent release of [3H]acetylcholine. In addition, BIMU 8 enhanced the release of [3H]acetylcholine and twitch contractions evoked by submaximal electrical stimulation. Ondansetron (1 μmol/l) did not change the effects of BIMU 8, but DAU 6285 and tropisetron (each 1 μmol/l) competitively antagonized the various facilitatory effects of BIMU 8 with pA2 values of 7.0–7.2 (DAU 6285) and 7.0–7.3 (tropisetron). The phosphodiesterase inhibitors IBMX and rolipram did not increase the effects of BIMU 8. BIMU 1 and renzapride also concentration-dependently increased basal release of acetylcholine, and release and contractions caused by submaximal stimulation. The effects of BIMU 1 and renzapride were competitively antagonized by 1 μmol/l tropisetron (pA2 6.6–7.1). The EC50 values for the increase in the evoked [3H]acetylcholine release and contractions were closely similar. 5-Hydroxyindalpine did not change basal release and slightly inhibited the evoked release of [3H]acetylcholine. Release of acetylcholine and contractions elicited by submaximal stimulation were strongly inhibited by (+)-tubocurarine which indicates that nicotinic ganglionic transmission is involved in this kind of release. The results suggest that BIMU 8, BIMU 1 and renzapride stimulate 5-HT4 receptors at cholinergic interneurones and thereby facilitate nicotinic ganglionic transmission in the myenteric plexus. Cyclic AMP is probably not involved in the 5-HT4 receptor mediated facilitation of acetylcholine release.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 229-236 
    ISSN: 1432-1912
    Keywords: BIMU 8 ; BIMU 1 ; Renzapride ; 5-HT4 receptors ; Acetylcholine release ; Myenteric plexus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of the 5-HT4 receptor agonists BIMU 8, BIMU 1, renzapride and of the 5-HT1p receptor agonist 5-hydroxyindalpine on basal and electrically evoked outflow of tritium were studied in guinea-pig longitudinal muscle myenteric plexus preparations preincubated with [3H]choline. Muscle contractions were recorded simultaneously. BIMU 8 caused a calcium dependent and tetrodotoxin sensitive increase in basal [3H]outflow that was assumed to represent release of [3H]acetylcholine. In addition, BIMU 8 enhanced the release of [3H]acetylcholine and twitch contractions evoked by submaximal electrical stimulation. Ondansetron (1 μmol/l) did not change the effects of BIMU 8, but DAU 6285 and tropisetron (each 1 μmol/l) competitively antagonized the various facilitatory effects of BIMU 8 with pA2 values of 7.0–7.2 (DAU 6285) and 7.0–7.3 (tropisetron). The phosphodiesterase inhibitors IBMX and rolipram did not increase the effects of BIMU 8. BIMU 1 and renzapride also concentration-dependently increased basal release of acetylcholine, and release and contractions caused by submaximal stimulation. The effects of BIMU 1 and renzapride were competitively antagonized by 1 μmol/l tropisetron (pA2 6.6–7.1). The EC50 values for the increase in the evoked [3H]acetylcholine release and contractions were closely similar. 5-Hydroxyindalpine did not change basal release and slightly inhibited the evoked release of [3H]acetylcholine. Release of acetylcholine and contractions elicited by submaximal stimulation were strongly inhibited by ( + )-tubocurarine which indicates that nicotinic ganglionic transmission is involved in this kind of release. The results suggest that BIMU 8, BIMU 1 and renzapride stimulate 5-HT4 receptors at cholinergic interneurones and thereby facilitate nicotinic ganglionic transmission in the myenteric plexus. Cyclic AMP is probably not involved in the 5-HT4 receptor mediated facilitation of acetylcholine release.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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