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Different effects of H1 and H2 blockers on the tone and the contractile activity of guinea pig stomach fundus.
Methods Find Exp Clin Pharmacol. 1995 Nov; 17(9):609-13.MF

Abstract

The action of H1 and H2 blockers on the spontaneous and evoked contractile activity of gastric fundus smooth muscles as well as the effects of H2 antagonists on the release of acetylcholine (ACh) from gastric myenteric neurons were studied. The experiments were performed on smooth muscle strips (25 x 3 mm) cut out in circular direction from guinea pig fundus region. In concentrations of 1 x 10(-7) M to 1 x 10(-4) M, the H1 blockers diphenhydramine (DPH), mepyramine (MEP) and dimethpyrindene (DMPD), but not the H2 blockers ranitidine (RAN), cimetidine (CIM) and roxatidine (ROX), increased in a concentration-dependent manner the smooth muscle tone, the maximum contractions being about 50% of the contractile effects of 1 x 10(-5) M ACH and 5 x 10(-5) M histamine (HA). The concentration-dependent contractions of the stomach fundus strips in response to electrical field stimulation (EFS) were enhanced by RAN, CIM and ROX (but not by MEP and DPH), all in concentrations of 1 x 10(-7) M to 1 x 10(-4) M. EFS increased the resting [3H]-ACh release by 67.8%, the S2/S1 ratio being 0.85 +/- 0.04. ROX in a concentration of 1 x 10(-5) M significantly increased (by 16.1%) the EFS-induced release with a S2/S1 ratio of 1.22 +/- 0.04. The ROX effect on the [3H]-ACh release was reduced or even abolished by 1 x 10(-6) M tetrodotoxin (TTX) and 1 x 10(-6) M scopolamine or in Ca(2+)-free medium, while 1 x 10(-6) M hexamethonium did not change it. It might be concluded that H2 blockers have no direct myogenic effect and do not interfere with muscarinic receptors in guinea pig stomach fundus. The H2 antagonists enhance the EFS-evoked contractions of the gastric smooth muscle most probably by increasing the release of ACH.

Authors+Show Affiliations

Institute of Physiology, Bulgarian Academy of Sciences, Sofia.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8786675

Citation

Milenov, K, et al. "Different Effects of H1 and H2 Blockers On the Tone and the Contractile Activity of Guinea Pig Stomach Fundus." Methods and Findings in Experimental and Clinical Pharmacology, vol. 17, no. 9, 1995, pp. 609-13.
Milenov K, Todorov S, Vassileva M, et al. Different effects of H1 and H2 blockers on the tone and the contractile activity of guinea pig stomach fundus. Methods Find Exp Clin Pharmacol. 1995;17(9):609-13.
Milenov, K., Todorov, S., Vassileva, M., Zamfirova, R., & Shahbazian, A. (1995). Different effects of H1 and H2 blockers on the tone and the contractile activity of guinea pig stomach fundus. Methods and Findings in Experimental and Clinical Pharmacology, 17(9), 609-13.
Milenov K, et al. Different Effects of H1 and H2 Blockers On the Tone and the Contractile Activity of Guinea Pig Stomach Fundus. Methods Find Exp Clin Pharmacol. 1995;17(9):609-13. PubMed PMID: 8786675.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Different effects of H1 and H2 blockers on the tone and the contractile activity of guinea pig stomach fundus. AU - Milenov,K, AU - Todorov,S, AU - Vassileva,M, AU - Zamfirova,R, AU - Shahbazian,A, PY - 1995/11/1/pubmed PY - 1995/11/1/medline PY - 1995/11/1/entrez SP - 609 EP - 13 JF - Methods and findings in experimental and clinical pharmacology JO - Methods Find Exp Clin Pharmacol VL - 17 IS - 9 N2 - The action of H1 and H2 blockers on the spontaneous and evoked contractile activity of gastric fundus smooth muscles as well as the effects of H2 antagonists on the release of acetylcholine (ACh) from gastric myenteric neurons were studied. The experiments were performed on smooth muscle strips (25 x 3 mm) cut out in circular direction from guinea pig fundus region. In concentrations of 1 x 10(-7) M to 1 x 10(-4) M, the H1 blockers diphenhydramine (DPH), mepyramine (MEP) and dimethpyrindene (DMPD), but not the H2 blockers ranitidine (RAN), cimetidine (CIM) and roxatidine (ROX), increased in a concentration-dependent manner the smooth muscle tone, the maximum contractions being about 50% of the contractile effects of 1 x 10(-5) M ACH and 5 x 10(-5) M histamine (HA). The concentration-dependent contractions of the stomach fundus strips in response to electrical field stimulation (EFS) were enhanced by RAN, CIM and ROX (but not by MEP and DPH), all in concentrations of 1 x 10(-7) M to 1 x 10(-4) M. EFS increased the resting [3H]-ACh release by 67.8%, the S2/S1 ratio being 0.85 +/- 0.04. ROX in a concentration of 1 x 10(-5) M significantly increased (by 16.1%) the EFS-induced release with a S2/S1 ratio of 1.22 +/- 0.04. The ROX effect on the [3H]-ACh release was reduced or even abolished by 1 x 10(-6) M tetrodotoxin (TTX) and 1 x 10(-6) M scopolamine or in Ca(2+)-free medium, while 1 x 10(-6) M hexamethonium did not change it. It might be concluded that H2 blockers have no direct myogenic effect and do not interfere with muscarinic receptors in guinea pig stomach fundus. The H2 antagonists enhance the EFS-evoked contractions of the gastric smooth muscle most probably by increasing the release of ACH. SN - 0379-0355 UR - https://www.unboundmedicine.com/medline/citation/8786675/Different_effects_of_H1_and_H2_blockers_on_the_tone_and_the_contractile_activity_of_guinea_pig_stomach_fundus_ DB - PRIME DP - Unbound Medicine ER -