English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

This study explored whether Staphylococcus aureus alpha-toxin can permeabilize the ventricular muscle and whether the treatment can leave cardiac membrane receptors, intracellular Ca2+ stores and the Ca2+ sensitivity of myofilament without damage. After alpha-toxin treatment, the trabeculae from guinea-pig ventricles developed tension at very low Ca2+ concentration ([Ca2+]) (approximately 0.6 microM) in high K+ solution. The trabeculae could contract transiently with 20 mM caffeine after incubating the muscle in a solution containing 0.5 microM [Ca2+]. Phenylephrine (20 microM) with or without GTP gamma S, a non-hydrolyzable analogue of GTP, in the incubating solution did not change the caffeine-induced tension transient. After loading intracellular Ca2+ stores with Ca2+, Ca2+ could be released from the stores by the [Ca2+] of 1.6 microM since the caffeine-induced tension transient was smaller than without Ca2+ releasing protocol. Phenylephrine with or without 100 microM GTP in the releasing solution did not modify the caffeine-induced tension transient. When the muscle was bathed in 1.6 microM Ca2+ solution containing 5 mM EGTA, the developed tension was maintained stably for more than 2 h. Phenylephrine with or without GTP, GTP alone, or 20 microM inositol 1,4,5-trisphosphate (InsP3) did not change the maintained tension. The amplitude and the rate of spontaneous contractions, induced at the free [Ca2+] around 0.5 microM, were not modified by phenylephrine, with or without GTP, and InsP3. These results show that alpha-toxin is useful at least to permeabilize the cardiac muscle to ions and small molecules without damaging the internal membrane and contractile machinery.

Contractility of .ALPHA.-Toxin Permeabilized Ventricular Muscle of Gunea Pig.