Histamine and the heart

1984 ◽  
Vol 62 (6) ◽  
pp. 720-726 ◽  
Author(s):  
John H. McNeill
Keyword(s):  
Histamine Receptor ◽  
Histamine Receptors ◽  
Ion Concentration ◽  
Free Calcium ◽  
Guinea Pig Heart ◽  
Release Of Noradrenaline ◽  
Chronotropic Effects ◽  
Calcium Ion Concentration ◽  
Right Atria ◽  
Stimulation Of

Histamine has been known as a cardiac stimulant for over 70 years. Work in our laboratory over the past decade has established that histamine receptors exist in the hearts of various species. The type of histamine receptor varies not only between species but also in the various regions of the heart. In the guinea pig heart H1 receptors are found in left atria and ventricles while H2 receptors are found in right atria and are the predominant histamine receptor in the ventricles. Rabbit atria contain both H1 and H2 receptors while the ventricles appear to possess only H1. Rat and cat heart do not seem to have histamine receptors and the positive inotropic and chronotropic effects elicited by histamine in cardiac preparations of these species are due to the release of noradrenaline. Dog heart contains H1 receptors while human heart has H2 receptors. In all cases H2 receptors are associated with adenylate cyclase and stimulation of such receptors results in an increase in cyclic AMP levels. H1 receptors are not associated with cyclic nucleotides in the heart. There are certain similarities between β-adrenergic and H2-histaminergic receptors as well as between α-adrenergic and H1-histaminergic receptors. Stimulation of either histamine receptor must result in an increase in the free calcium ion concentration in the cardiac cell but the mechanisms involved are obviously different.

scholarly journals Fluorescence anisotropy imaging microscopy maps calmodulin binding during cellular contraction and locomotion.

1993 ◽  
Vol 121 (5) ◽  
pp. 1095-1107 ◽  
Author(s):  
A H Gough ◽  
D L Taylor
Keyword(s):  
Wound Healing ◽  
Fluorescence Anisotropy ◽  
Calcium Ion ◽  
Myosin Ii ◽  
Ion Concentration ◽  
Free Calcium ◽  
Target Proteins ◽  
Calmodulin Binding ◽  
Calcium Ion Concentration ◽  
Stimulation Of

Calmodulin is a calcium transducer that activates key regulatory and structural proteins through calcium-induced binding to the target proteins. A fluorescent analog of calmodulin in conjunction with ratio imaging, relative to a volume indicator, has demonstrated that calmodulin is uniformly distributed in serum-deprived fibroblasts and there is no immediate change in the distribution upon stimulation with complete serum. The same fluorescent analog of calmodulin together with steady state fluorescence anisotropy imaging microscopy has been used to define the temporal and spatial changes in calmodulin binding to cellular targets during stimulation of serum-deprived fibroblasts and in polarized fibroblasts during wound healing. In serum-deprived fibroblasts, which exhibit a low free calcium ion concentration, a majority of the fluorescent analog of calmodulin remained unbound (fraction bound, fB < 10%). However, upon stimulation of the serum-deprived cells with complete serum, calmodulin binding (maximum fB approximately 95%) was directly correlated with the time course of the elevation and decline of the free calcium ion concentration, while the contraction of stress fibers continued for an hour or more. Calmodulin binding was also elevated in the leading lamellae of fibroblasts (maximum FB approximately 50%) during the lamellar contraction phase of wound healing and was spatially correlated with the contraction of transverse fibers containing myosin II. Highly polarized and motile fibroblasts exhibited the highest anisotropy (calmodulin binding) in the retracting tails and in association with contracting transverse fibers in the cortex of the cell. These results suggest that local activation of myosin II-based contractions involves the local binding of calmodulin to target proteins. The results also demonstrate a powerful yet simple mode of light microscopy that will be valuable for mapping molecular binding of suitably labeled macromolecules in living cells.

scholarly journals Injection of inositol trisphosphorothioate into Limulus ventral photoreceptors causes oscillations of free cytosolic calcium.

1991 ◽  
Vol 97 (6) ◽  
pp. 1165-1186 ◽  
Author(s):  
R Payne ◽  
B V Potter
Keyword(s):  
Membrane Potential ◽  
Calcium Release ◽  
Feedback Inhibition ◽  
Initial Response ◽  
Periodic Variation ◽  
Cytosolic Calcium ◽  
Ion Concentration ◽  
Free Calcium ◽  
Calcium Stores ◽  
Calcium Ion Concentration

Limulus ventral photoreceptors contain calcium stores sensitive to release by D-myo-inositol 1,4,5 trisphosphate (InsP3) and a calcium-activated conductance that depolarizes the cell. Mechanisms that terminate the response to InsP3 were investigated using nonmetabolizable DL-myo-inositol 1,4,5 trisphosphorothioate (InsPS3). An injection of 1 mM InsPS3 into a photoreceptor's light-sensitive lobe caused an initial elevation of cytosolic free calcium ion concentration (Cai) and a depolarization lasting only 1-2 s. A period of densensitization followed, during which injections of InsPS3 were ineffective. As sensitivity recovered, oscillations of membrane potential began, continuing for many minutes with a frequency of 0.07-0.3 Hz. The activity of InsPS3 probably results from the D-stereoisomer, since L-InsP3 was much less effective than InsP3. Injections of 1 mM InsP3 caused an initial depolarization and a period of densensitization similar to that caused by 1 mM InsPS3, but no sustained oscillations of membrane potential. The initial response to InsPS3 or InsP3 may therefore be terminated by densensitization, rather than by metabolism. Metabolism of InsP3 may prevent oscillations of membrane potential after sensitivity has recovered. The InsPS3-induced oscillations of membrane potential accompanied oscillations of Cai and were abolished by injection of ethyleneglycol-bis (beta-aminoethyl ether)-N,N'-tetraacetic acid. Removal of extracellular calcium reduced the frequency of oscillation but not its amplitude. Under voltage clamp, oscillations of inward current were observed. These results indicate that periodic bursts of calcium release underly the oscillations of membrane potential. After each burst, the sensitivity of the cell to injected InsP3 was greatly reduced, recovering during the interburst interval. The oscillations may, therefore, result in part from a periodic variation in sensitivity to a constant concentration of InsPS3. Prior injection of calcium inhibited depolarization by InsPS3, suggesting that feedback inhibition of InsPS3-induced calcium release by elevated Cai may mediate desensitization between bursts and after injections of InsPS3.

Bile canalicular contraction in the isolated hepatocyte doublet is related to an increase in cytosolic free calcium ion concentration

2008 ◽  
Vol 8 (3) ◽  
pp. 178-183 ◽  
Author(s):  
Sumio Watanabe ◽  
Masahiro Tomono ◽  
Makoto Takeuchi ◽  
Tsuneo Kitamura ◽  
Miyoko Hirose ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Ion Concentration ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Bile Canalicular Contraction ◽  
Calcium Ion Concentration

scholarly journals The gravistimulation-induced very slow Ca2+ increase in Arabidopsis seedlings requires MCA1, a Ca2+-permeable mechanosensitive channel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masataka Nakano ◽  
Takuya Furuichi ◽  
Masahiro Sokabe ◽  
Hidetoshi Iida ◽  
Hitoshi Tatsumi
Keyword(s):  
Calcium Ion ◽  
Channel Blocker ◽  
Upright Position ◽  
Ion Concentration ◽  
Early Event ◽  
Free Calcium ◽  
Permeable Channel ◽  
Mechanosensitive Ion Channel ◽  
And Function ◽  
Calcium Ion Concentration

AbstractGravity is a critical environmental factor affecting the morphology and function of plants on Earth. Gravistimulation triggered by changes in the gravity vector induces an increase in the cytoplasmic free calcium ion concentration ([Ca2+]c) as an early process of gravity sensing; however, its role and molecular mechanism are still unclear. When seedlings of Arabidopsis thaliana expressing apoaequorin were rotated from the upright position to the upside-down position, a biphasic [Ca2+]c-increase composed of a fast-transient [Ca2+]c-increase followed by a slow [Ca2+]c-increase was observed. We find here a novel type [Ca2+]c-increase, designated a very slow [Ca2+]c-increase that is observed when the seedlings were rotated back to the upright position from the upside-down position. The very slow [Ca2+]c-increase was strongly attenuated in knockout seedlings defective in MCA1, a mechanosensitive Ca2+-permeable channel (MSCC), and was partially restored in MCA1-complemented seedlings. The mechanosensitive ion channel blocker, gadolinium, blocked the very slow [Ca2+]c-increase. This is the first report suggesting the possible involvement of MCA1 in an early event related to gravity sensing in Arabidopsis seedlings.

Dependence of Cardiac Contractility on Myofibrillar Calcium Sensitivity

Physiology ◽  
1987 ◽  
Vol 2 (5) ◽  
pp. 179-182
Author(s):  
JC Ruegg
Keyword(s):  
Calcium Ion ◽  
Sarcomere Length ◽  
Cardiac Contractility ◽  
Calcium Sensitivity ◽  
Ion Concentration ◽  
Free Calcium ◽  
Wide Range ◽  
Heart Contractility ◽  
Calcium Ion Concentration

In the heart, contractility may be varied over a wide range. It is determined mainly by the myoplasmic free calcium ion concentration. However, alteration of the responsiveness of the myofilaments to calcium may also be important in regulating cardiac contractility, in particular following changes in sarcomere length, or in hypoxia, or after interventions with certain novel cardiotonic drugs.

Effect of calcium on neurohumoral stimulation of feline colonic smooth muscle

1982 ◽  
Vol 243 (2) ◽  
pp. G134-G140
Author(s):  
W. J. Snape
Keyword(s):  
Smooth Muscle ◽  
Spike Activity ◽  
Calcium Ion ◽  
Calcium Concentration ◽  
Extracellular Calcium ◽  
Ion Concentration ◽  
Myoelectric Activity ◽  
Ionic Calcium ◽  
Calcium Ion Concentration ◽  
Stimulation Of

The purpose of this study was to compare the effect of altering the extracellular calcium ion concentration on bethanechol or octapeptide of cholecystokinin (OP-CCK) stimulation of the isolated transverse colon of the cat. Myoelectric activity was recorded with monopolar glass-pore electrodes. Bethanechol (10(-6) M) stimulated an increase in the number of slow waves with superimposed spike potentials to 85.5 +/- 5.3% (P less than 0.001) compared with the basal spike activity (8.9 +/- 1.4%). OP-CCK (4 x 10(-9)) also increased spike activity (80.7 +/- 3.8%, P less than 0.001), which was not inhibited by atropine, phentolamine, or propranolol. Addition of 0.0 mM calcium solution to the colonic smooth muscle abolished both slow-wave and spike activity, which returned after replacing 0.25 mM calcium in the solution. Bethanechol stimulated a greater increase in spike activity as the concentration of calcium was increased. OP-CCK stimulation of colonic spike activity was more sensitive to the extracellular calcium concentration than bethanechol stimulation. Verapamil had a minimal effect on bethanechol stimulation of colonic spike activity, but it inhibited the OP-CCK stimulation. These studies suggest that 1) OP-CCK appears to stimulate colonic smooth muscle directly and 2) OP-CCK requires the presence of a greater amount of extracellular ionic calcium in order to stimulate colonic spike activity compared with bethanechol.

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