The control of the contraction of myocytes from guinea‐pig heart by the resting membrane potential

Mermi, Johann; Yajima, Michio; Ebner, F.

doi:10.1111/j.1476-5381.1991.tb12492.x

Cited by 7 publications

(4 citation statements)

References 54 publications

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“…Depending on the experiment, the free Ca 2+ concentration was changed from 10 nM to 3 µM by changing the Ca 2+ concentration in the corresponding solution. The appropriate amounts of CaCl 2 were added, and the pH adjusted according to a computer programme [22] on the basis of the binding constants of Fabiato [9] and checked by fura-2 fluorescence.…”

Section: Solutionsmentioning

confidence: 99%

Regulation of stably expressed and native BK channels from human myometrium by cGMP- and cAMP-dependent protein kinase

Zhou¹,

Schlossmann²,

Hofmann³

et al. 1998

Pfl�gers Archiv European Journal of Physiology

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The cloned BK channel alpha subunit from human myometrium was stably expressed in Chinese hamster ovary cells, either alone (CHOalpha cells) or in combination with the auxiliary beta subunit (CHOalpha+beta cells). We studied basic channel properties and the effects of cGMP- and cAMP-dependent protein kinases on the BK channel activity. Coexpression of alpha and beta subunits enhanced the Ca2+ and voltage sensitivity of the BK channel, and decreased the inhibitory potency of iberiotoxin. Blocking and stimulating effects on BK channel activity by charybdotoxin and nitric oxide, respectively, were independent of the beta subunit. The cGMP kinase Ialpha and cAMP kinase failed to affect BK channel activity in CHOalpha and CHOalpha+beta cells at different [Ca2+]i and voltages. In contrast, BK channels in freshly isolated myometrial cells from postmenopausal women responded to cAMP kinase and cGMP kinase with a fourfold and twofold decrease in their open probability (NPo), respectively. These effects could be reversed by alkaline phosphatase and remained unaffected by the phosphatase inhibitor okadaic acid (100 nM). In 28% of myometrial cells, however, cAMP and cGMP kinases increased NPo 2-fold and 3.5-fold, respectively. This stimulation was enhanced rather than reversed by alkaline phosphatase and was abolished by 100 nM okadaic acid. The results suggest that in stably transfected CHO cells the expressed BK channel is not regulated by cAMP kinase and cGMP kinase. However, in native myometrial cells stimulatory and inhibitory regulation of BK channels by cAMP kinase and cGMP kinase was observed, suggesting that channel regulation by the protein kinases requires factors that are not provided by CHO cells. Alternatively, failure of regulation may have been due to the primary structure of the myometrial BK channel protein used in this study.

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Section: Solutionsmentioning

confidence: 99%

Regulation of stably expressed and native BK channels from human myometrium by cGMP- and cAMP-dependent protein kinase

Zhou¹,

Schlossmann²,

Hofmann³

et al. 1998

Pfl�gers Archiv European Journal of Physiology

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show abstract

“…Depending on the experiment, the free calcium concentration was changed from 0 to 1 M by changing the calcium concentration in the corresponding solution. The appropriate amounts of CaCl 2 were added pH-adjusted according to a computer program (25) on the basis of the binding constants of Fabiato (26).…”

Section: Solutionsmentioning

confidence: 99%

Protein Phosphatase 2A Is Essential for the Activation of Ca2+-activated K+ Currents by cGMP-dependent Protein Kinase in Tracheal Smooth Muscle and Chinese Hamster Ovary Cells

Zhou¹,

Ruth²,

Schlossmann³

et al. 1996

Journal of Biological Chemistry

121

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“…Since the viscosity of the drug loaded micellar formulations did not change significantly it probably indicates that the drug loaded micelles were mostly spherical/ellipsoid in shape. Literature reports also suggest that surfactants listed in Table II form spherical/ellipsoid shaped micelles in dilute solutions (42-46). …”

Section: Discussionmentioning

confidence: 98%

Ocular Disposition of the Hemiglutarate Ester Prodrug of ∆9-Tetrahydrocannabinol from Various Ophthalmic Formulations

et al. 2013

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Purpose The overall goal of this project is to enhance ocular delivery of ∆9-Tetrahydrocannabinol (THC) through the topical route. Methods Solubility, stability and in vitro transcorneal permeability of the relatively hydrophilic hemiglutarate ester derivative, THC-HG, was studied in the presence of surfactants. The solutions were characterized with respect to micelle size, zeta potential and solution viscosity. In vivo studies were carried out in New Zealand albino rabbits. A previously reported promising THC-HG ion-pair formulation was also studied in vivo. Results Aqueous solubility and stability and in vitro transcorneal permeability of THCHG was enhanced significantly in the presence of surfactants. THC levels in the ocular tissues (except cornea) were found to be below detection limits from mineral oil, surfactant or emulsion based formulations containing THC. In contrast, micellar and ion pair based THC-HG formulations produced significantly higher total THC concentrations in the anterior ocular chamber. Conclusion In this study, although delivery of THC to the anterior chamber ocular tissues could be significantly increased through the prodrug and formulation approaches tested, further studies are needed to increase penetration to the back-of-the eye.

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The control of the contraction of myocytes from guinea‐pig heart by the resting membrane potential

Cited by 7 publications

References 54 publications

Regulation of stably expressed and native BK channels from human myometrium by cGMP- and cAMP-dependent protein kinase

Regulation of stably expressed and native BK channels from human myometrium by cGMP- and cAMP-dependent protein kinase

Protein Phosphatase 2A Is Essential for the Activation of Ca2+-activated K+ Currents by cGMP-dependent Protein Kinase in Tracheal Smooth Muscle and Chinese Hamster Ovary Cells

Ocular Disposition of the Hemiglutarate Ester Prodrug of ∆9-Tetrahydrocannabinol from Various Ophthalmic Formulations

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