Mechanisms underlying spontaneous rhythmical contractions in irideal arterioles of the rat
Hill, Caryl; Eade, Joyce; Sandow, Shaun L
Description
1. Mechanisms underlying spontaneous rhythmical contractions have been studied in irideal arterioles of the rat using video microscopy and electrophysiology. 2. Rhythmical contractions (4 min-1) were more common during the second and third postnatal weeks and were always preceded by large, slow depolarizations (5-40 mV). 3. Spontaneous contractions were unaffected by tetrodotoxin (1 μM), neurotransmitter receptor antagonists, the sympathetic neurone blocker, guanethidine (5 μM) or sensory...[Show more]
dc.contributor.author | Hill, Caryl | |
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dc.contributor.author | Eade, Joyce | |
dc.contributor.author | Sandow, Shaun L | |
dc.date.accessioned | 2015-12-13T23:23:56Z | |
dc.identifier.issn | 0022-3751 | |
dc.identifier.uri | http://hdl.handle.net/1885/91991 | |
dc.description.abstract | 1. Mechanisms underlying spontaneous rhythmical contractions have been studied in irideal arterioles of the rat using video microscopy and electrophysiology. 2. Rhythmical contractions (4 min-1) were more common during the second and third postnatal weeks and were always preceded by large, slow depolarizations (5-40 mV). 3. Spontaneous contractions were unaffected by tetrodotoxin (1 μM), neurotransmitter receptor antagonists, the sympathetic neurone blocker, guanethidine (5 μM) or sensory neurotoxin, capsaicin (1 μM). 4. Stimulation of sensory nerves inhibited spontaneous activity and this was not prevented by L-NAME (10 μM). 5. L-NAME (10 μM) caused an increase in frequency of spontaneous contractions, while forskolin (30 nM), in the presence of L-NAME, abolished spontaneous, but not nerve-mediated, contractions. 6. Spontaneous activity was not affected by felodipine (1 nM) or nifedipine (1 μM), but was abolished by cadmium chloride (1 μM) or superfusion with calcium-free solution. 7. Caffeine (1 mM), thapsigargin (2 μM) and cyclopiazonic acid (3 μM), but not ryanodine (3 μM), abolished spontaneous and nerve-mediated contractions. After preincubation in L-NAME (10 μM), cyclopiazonic acid abolished spontaneous contractions only. 8. Spontaneous depolarizations and contractions were abolished by 18α-glycyrrhetinic acid (20 μM). 9. Results suggest that spontaneous rhythmical contractions are myogenic and result from the cyclical release of calcium from intracellular stores, without a contribution from voltage-dependent calcium channels. Intercellular coupling through gap junctions appears to be essential for co-ordination of these events which could be modulated by nitric oxide and increases in cAMP. The possibility that different intracellular stores underly spontaneous and nerve-mediated contractions is discussed. | |
dc.publisher | Cambridge University Press | |
dc.source | Journal of Physiology | |
dc.subject | Keywords: 18alpha glycyrrhetinic acid; cadmium chloride; caffeine; calcium channel; capsaicin; cyclic AMP; cyclopiazonic acid; felodipine; guanethidine; n(g) nitroarginine methyl ester; neurotoxin; nifedipine; nitric oxide; ryanodine; tetrodotoxin; thapsigargin; an | |
dc.title | Mechanisms underlying spontaneous rhythmical contractions in irideal arterioles of the rat | |
dc.type | Journal article | |
local.description.notes | Imported from ARIES | |
local.description.refereed | Yes | |
local.identifier.citationvolume | In press | |
dc.date.issued | 1999 | |
local.identifier.absfor | 060602 - Animal Physiology - Cell | |
local.identifier.ariespublication | MigratedxPub22935 | |
local.type.status | Published Version | |
local.contributor.affiliation | Hill, Caryl, College of Medicine, Biology and Environment, ANU | |
local.contributor.affiliation | Eade, Joyce, Murdoch University | |
local.contributor.affiliation | Sandow, Shaun L, College of Medicine, Biology and Environment, ANU | |
local.description.embargo | 2037-12-31 | |
local.bibliographicCitation.startpage | 507 | |
local.bibliographicCitation.lastpage | 516 | |
dc.date.updated | 2015-12-12T09:18:17Z | |
local.identifier.scopusID | 2-s2.0-0033407095 | |
Collections | ANU Research Publications |
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