Role of sarcoplasmic reticulum in the myorelaxant activity of nitric oxide donors in guinea pig gastric fundus

Georgi Petkov, Georgi D. Spassov, Kiril K. Boev

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The relaxant effect of two nitric oxide (NO) donors: sodium nitroprusside and 3-morpholino-sydnonimine (SIN-1) on circular smooth muscle strips isolated from guinea pig gastric fundus was studied with the view to elucidating the mechanism, which underlies the NO-induced relaxation of this tissue. Both sodium nitroprusside (10-9-10-5 M) and SIN-1 (10-9-10-4 M) suppressed the spontaneous fundus tone and hyperpolarized the muscle cells by about 5 mV. They antagonized the acetylcholine (10-6 M)-induced tone and exerted their relaxant effects even when Ca2+ influx into the cells was triggered through the Na+/Ca2+ exchanger. Sodium nitroprusside and SIN-1 antagonized the contraction induced by cyclopiazonic acid (10-5 M), a specific inhibitor of the sarcoplasmic reticulum Ca2+-ATPase. In the presence of high concentrations of sodium nitroprusside or SIN-1, cyclopiazonic acid (10-5 M) exerted only a slight if any contractile effect. After the complete relaxation induced by sodium nitroprusside or SIN-1, the K+-channel blockers, tetraethylammonium, apamin and charybdotoxin, as well as the Ca2+ ionophore, A 23187, induced high-amplitude contractions, suggesting that the Ca2+ sensitivity of the contractile myofilaments was not affected. The results suggest that NO, released from NO donors increases the sarcoplasmic reticulum Ca2+ uptake thereby enhancing the vectorial sarcoplasmic reticulum Ca2+ release toward the plasmalemma to elicit membrane hyperpolarization and relaxation in guinea pig gastric fundus. Copyright (C) 1998 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)59-66
Number of pages8
JournalEuropean Journal of Pharmacology
Volume354
Issue number1
DOIs
StatePublished - Jul 31 1998

Fingerprint

Gastric Fundus
Nitric Oxide Donors
Sarcoplasmic Reticulum
Nitroprusside
Guinea Pigs
Nitric Oxide
Molsidomine
Charybdotoxin
Apamin
Tetraethylammonium
Calcium-Transporting ATPases
Myofibrils
Ionophores
Calcimycin
Muscle Cells
Acetylcholine
Smooth Muscle
Membranes

All Science Journal Classification (ASJC) codes

  • Cellular and Molecular Neuroscience
  • Pharmacology

Cite this

Role of sarcoplasmic reticulum in the myorelaxant activity of nitric oxide donors in guinea pig gastric fundus. / Petkov, Georgi; Spassov, Georgi D.; Boev, Kiril K.

In: European Journal of Pharmacology, Vol. 354, No. 1, 31.07.1998, p. 59-66.

Research output: Contribution to journalArticle

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