Die bestudering van die meganisme van hartspierkontraksie met behulp van kalium-kontraktuur

Abstract

In the above study potassium contracture was used. This study showed that two characteristic kinds of potassium contracture patterns occured which consisted of different components or phases. However in both contracture patterns a plateau component occured which was readily rendered. It is therefore in this plateau component that the interest lies. By means of Ca-free solutions and lanthanum it was attempted to seperate and to identify the different components or phases (3.4). From this identification it was proved that the second phase, the plateau component and the third phase originated from a resulting calsium influx through the cell membrane. The first phase originates most probably as a result of the calsium release from the sarcoplasmic reticulum. Further experiments showed that above mentioned plateau component was dependant on the external potassium consentration (3.2 and 3.5.1) and the external sodium consentration (3.3 and 3.5.2). Seeing that the plateau component originates form a resulting calsium influx through the cell membrane it seems thus that this resulting calsium influx greatly depends on the external potassium consentration. In other word the membrane protential ( 3.2 and 3.5.1 ). The resulting calsium influx through the cell membrane is also dependant on the external sodium consentration (3.3 and 3.5.2). Considering that the free intracellular calsium consentration is dependant on the resulting calsium influx or the effective membrane permeability we come to the conclusion that the free intracellular calsium consentration will be stipulated through the extracellular potassium - and sodium consentration. The influence of adrenaline and caffeïene were also examined (5.1 and 5.2). The results indicated that both adrenaline and caffeïene brought a increase in the plateau component. Seeing that this plateau component is an indirect function of the free intracellular calsiwn consentration it appears that both adrenaline and caffeïene bring an increase in the free intracellular calsium consentration. However the way in which these two substances bring an increase in the free intracellular calsium consentration is indeffinate.