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Measurements of simultaneous force and intracellular Ca2+ concentration ([Ca2+]i) in rat uterine smooth muscle have been made to elucidate the mechanisms involved when force produced spontaneously, by high-K+ depolarization or carbachol is altered by a change of intracellular pH (pHi). Rises in force and [Ca2+]i were closely correlated for all forms of(More)
Although there is evidence that caveolae and cholesterol play an important role in myocyte signalling processes, details of the mechanisms involved remain sparse. In this paper we have studied for the first time the clinically relevant intact coronary artery and measured in situ Ca(2+) signals in individual myocytes using confocal microscopy. We have(More)
1. We have investigated the effect of cyclopiazonic acid (CPA), an inhibitor of the sarcoplasmic reticulum (SR) Ca2+-ATPase on excitation-contraction (EC) coupling in guinea-pig ureter, by measuring membrane currents, action potentials, intracellular [Ca2+] and force. 2. CPA (20 micrometers) significantly enhanced the amplitude and duration of phasic(More)
1. We investigated the relationship between the action potential, Ca2+ and phasic force in intact guinea-pig ureter, following physiological activation. 2. The action potential elicited a Ca2+ transient consisting of three components: a fast increment, associated with the first action potential spike, a slower increment, associated with subsequent spikes(More)
Calcium signalling in smooth muscles is complex, but our understanding of it has increased markedly in recent years. Thus, progress has been made in relating global Ca2+ signals to changes in force in smooth muscles and understanding the biochemical and molecular mechanisms involved in Ca2+ sensitization, i.e. altering the relation between Ca2+ and force.(More)
The sarcoplasmic reticulum (SR) of smooth muscles presents many intriguing facets and questions concerning its roles, especially as these change with development, disease, and modulation of physiological activity. The SR's function was originally perceived to be synthetic and then that of a Ca store for the contractile proteins, acting as a Ca amplification(More)
In excitable tissues the refractory period is a critical control mechanism preventing hyperactivity and undesirable tetani, by preventing subsequent stimuli eliciting action potentials and Ca2+ entry. In ureteric smooth muscle, peristaltic waves that occur as invading pacemaker potentials produce long-lasting action potentials (300-800 ms) and(More)
OBJECTIVES The aim of this study was to investigate the temporal and spatial characteristics of spontaneous Ca signals in pregnant rat myometrium. STUDY DESIGN Confocal imaging of longitudinal strips of 21-day pregnant rats loaded with the Ca sensitive indicator Fluo-4, was combined with measurements of mechanical activity in uterine smooth muscle cells,(More)
Controlled uterine smooth muscle activity is essential for our reproductive health. While we understand reasonably well the steps that produce contraction following a rise in intracellular [Ca], the mechanism controlling excitability and thus the rise of Ca, is less well understood. Here we examine the role of the internal Ca sore, the sarcoplasmic(More)
1. We have investigated the internal Ca2+ store and its ability to affect contraction by simultaneously measuring force and Ca2+ in the ureter from guinea-pig and rat. Both species responded in a similar manner to electrical stimulation and depolarization with high-K+, generating plateau-type action potentials and increasing intracellular calcium ([Ca2+]i)(More)