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Full-Text Articles in Medicine and Health Sciences

Ryanodine Receptor Adaptation, Michael Fill, A. Zahradníková, Carlos A. Villalba-Galea, I. Zahradník, A. L. Escobar, S. Györke Dec 2000

Ryanodine Receptor Adaptation, Michael Fill, A. Zahradníková, Carlos A. Villalba-Galea, I. Zahradník, A. L. Escobar, S. Györke

School of Pharmacy Faculty Articles

In the heart, depolarization during the action potential activates voltage-dependent Ca2+ channels that mediate a small, localized Ca2+ influx (ICa). This small Ca2+ signal activates specialized Ca2+ release channels, the ryanodine receptors (RyRs), in the sarcoplasmic reticulum (SR). This process is called Ca2+-induced Ca2+ release (CICR). Intuitively, the CICR process should be self-regenerating because the Ca2+ released from the SR should feedback and activate further SR Ca2+ release. However, the CICR process is precisely controlled in the heart and, consequently, some sort of negative control mechanism(s) must exist to …


Effect Of Calcium, Magnesium, Sodium And Potassium Levels In Seminal Plasma Of Holstein Bulls On Spermatological Characters, Seyfetti̇n Gür, Eşref Demi̇rci̇ Jan 2000

Effect Of Calcium, Magnesium, Sodium And Potassium Levels In Seminal Plasma Of Holstein Bulls On Spermatological Characters, Seyfetti̇n Gür, Eşref Demi̇rci̇

Turkish Journal of Veterinary & Animal Sciences

This study was conducted to investigate the levels calcium, magnesium, sodium and potassium in the seminal plasma of bulls, semen volume, sperm motility, sperm concentration and the correlation between these parametres. Five Holstein bulls constituted the material of this study. Twenty ejaculates were collected from each bull and the spermatological characteristics of these ejaculates were determined. Then, seminal plasma was separated from 3ml semen from each ejaculate by centrifugation at 1500g for 20 min at 4 °C. Calcium, magnesium, sodium and potassium concentrations in seminal plasma were determined by atomic absorption spectrophotometry. The average values for calcium, magnesium, sodium and …