{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2024,6,17]],"date-time":"2024-06-17T20:37:44Z","timestamp":1718656664711},"reference-count":0,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[1993,1,1]],"date-time":"1993-01-01T00:00:00Z","timestamp":725846400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[1993,1]]},"abstract":"<jats:p>1. The relationships between cytosolic Ca2+ ([Ca2+]cyt; expressed as a fluorescence ratio at 400 nm and 500 nm using Indo\u20101) and contractile force was examined in strips of circular smooth muscles of canine gastric antrum. Rhythmic increases in [Ca2+]cyt were observed and contractions were biphasic. 2. In most muscles (70%), the amplitude of the second phase of the Ca2+ transient was less than or equal to the first phase of the Ca2+ transient, but the second phase of the contraction was much smaller than the first phase, suggesting a decrease in Ca2+ sensitivity during the second contractile phase. In 30% of muscles, the amplitude of the second phase of the Ca2+ transient was 2\u2010 to 3\u2010fold greater than the first phase. In these muscles, the second phase of contraction was 10\u2010fold greater than the first phase of contraction. Thus, a non\u2010linear relationship between [Ca2+]cyt and force greatly amplifies force development when [Ca2+]cyt exceeds a threshold level. 3. Acetylcholine (ACh, 0.3\u20101 microM) increased the amplitudes of Ca2+ transients and basal [Ca2+]cyt between phasic contractions. The increase in basal [Ca2+]cyt did not cause tone to develop. ACh increased the amplitude of Ca2+ transients 2\u2010 to 3\u2010fold and this was associated with a 15 to 20\u2010fold increase in the force of phasic contractions. Pentagastrin (0.5 nM) and cholecystokinin octapeptide (CCK, 40 nM) had similar effects on Ca2+ transients and phasic contractions. 4. Bay K 8644 (0.1 microM) and TEA (5 mM) also increased the amplitudes of Ca2+ transients by 2\u2010 to 3\u2010fold and phasic contractions by 15\u2010 to 30\u2010fold. There was no significant difference observed between the [Ca2+]cyt\u2010force relationships in the presence of agonists (i.e. ACh, pentagastrin and CCK) or when [Ca2+]cyt was increased by Bay K 8644 or TEA. These data suggest that agonist\u2010dependent increases in Ca2+ sensitivity may not significantly regulate the [Ca2+]cyt\u2010force relationship in antral muscles. 5. D600 (5 microM), added during stimulation with ACh (0.3 M), decreased [Ca2+]cyt and force without affecting the [Ca2+]cyt\u2010force relationship. 6. Mechanisms exist for agonist\u2010mediated enhancement of the Ca(2+)\u2010force relationship. In alpha\u2010toxin\u2010permeabilized antrum, ACh (10 microM) with GTP (100 microM) or GTP gamma S (100 microM) increased the Ca(2+)\u2010induced contraction at clamped levels of Ca2+. Phorbol 12,13\u2010dibutyrate (PDBu, 10 microM) also increased the contractile force at a given level of Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS)<\/jats:p>","DOI":"10.1113\/jphysiol.1993.sp019457","type":"journal-article","created":{"date-parts":[[2014,12,17]],"date-time":"2014-12-17T14:59:45Z","timestamp":1418828385000},"page":"33-50","source":"Crossref","is-referenced-by-count":19,"title":["Ca2+ regulation of the contractile apparatus in canine gastric smooth muscle."],"prefix":"10.1113","volume":"460","author":[{"given":"H","family":"Ozaki","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"W T","family":"Gerthoffer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M","family":"Hori","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"H","family":"Karaki","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"K M","family":"Sanders","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"N G","family":"Publicover","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[1993,1]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1993.sp019457","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1993.sp019457","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,25]],"date-time":"2023-10-25T15:00:38Z","timestamp":1698246038000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1993.sp019457"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,1]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1993,1]]}},"alternative-id":["10.1113\/jphysiol.1993.sp019457"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1993.sp019457","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1993,1]]}}}