heart mechanics
The purpose of this experiment was to subject a rat cardiac muscle to different physiological situations and determine their effect on the twitch force and duration. Force-frequency relation show a positive trend suggesting that as frequency of stimulation increases (for the range of 0.2-0.8 Hz), the force increases. Also the extra cellular calcium concentration effects on the peak force were measured, showed an increasing trend when the [Ca2+ ]o was incrementally increased from 0.2 to 3mmolL-1. The rat cardiac muscle was also subjected to cardiac glycoside such as ouabain, which resulted in an increase in the diastolic force, inotropic agents such as isoprenaline, which increased the velocity of contractility, and finally the effects of caffeine were considered.We were provided with a ventricular strip of a rat heart muscle; it had the dimensions of (~20mm resting length, 5mm wide and 1mm thick). The strip was embedded in an oxygenated 1.5mM Ca2+ Tyrode solution (constant PH=7.4) with constant O2 partial pressure of oxygen is 760 mmHg, because the cell needs oxygen in order to survive, the strip mounted using threads to a force transducer and a stimulator (REF1), these were conne
Figure 4: Peak force as a function of extra cellular calcium Figure 5: duration as a function of extra cellular Calcium concentration. Force and extra cellular calcium concentration relation:The force - [Ca2+ ]o relation indicate in increase of twitch force when the [Ca2+ ]o is increased (at least up to 3mmolL-1) for a given frequency, a possible reason could be that as the [Ca2+ ]o increases there will be more calcium entering the cell up on stimulation because the concentration gradient has increased, causing the SR to release more calcium and increasing contraction force (as discussed above). 8Hz) would cause an increase in contraction force ; this is the case in most species other than rats. Discussion:Force-frequency relation:The frequency force relation suggests that an increase in stimulation frequency (from 0. Isoprenaline would not affect skeletal muscle because sympathetic nerves do not innervate skeletal muscle, and it is a voluntary muscle. 4Hz stimulus was applied to the muscle at control conditions then, the bath was filled with the provided caffeine solution (containing 10 mmolL-1 caffeine and 1. With respect to skeletal muscle increasing frequency would also increase twitch force. 2 mmolL-1 to 3 mmolL-1 the peak force shows an increasing trend, See figure4, with a large increase from 0. Results from the ouabain experiment:* There is a small change in half width (from 0. 4 mmolL-1 of Ca2+ were added to the solution and steady state force of a single twitch was captured at each new added amount.
Common topics in this essay:
Na K-ATPase,
Effect Isoprenaline,
Ca2+ Tyrode,
Results Ca2+,
Results Frequency,
CICR Calcium,
Discussion Force-frequency,
,
Method Experimental,
Ca2+ Effects,
half width,
peak force,
rat cardiac muscle,
twitch force,
cardiac muscle,
rat cardiac,
extra cellular,
calcium concentration,
skeletal muscle,
diastolic force,
cellular calcium,
extra cellular calcium,
cellular calcium concentration,
increase diastolic force,
twitch force increases,
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Acceptance Essays
