Analysis of inward I Na and I Ca also showed these currents were significantly smaller compared to adult cells Regional differences of I K1 density have been reported. I to is completely absent in myocytes from 2 weeks Figure 3. Single myocytes isolated from the left ventricle of week old canine neonate hearts were studied using patch-clamp techniques. These results suggest that the underlying ionic currents are different at different stages of development. I K1 density in adult midmyocardial cells was less than that seen in neonate ventricular cells. Hope that helps in figuring out an answer.

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Protocol repeated in the presence of nM isoproterenol. In the adult mammalian heart, marked differences in the shape and duration of the cardiac action potential have been well described in different regions of ventricle [ 3 – 5 ].

Hume JR, Uehara A.

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CsClMgCl 2 1. J Physiol Lond ; Pt 1: Cardiac pacemaking in the sinoatrial node. Since peak I Na during the 25 ms test h25221 was reduced in neonate cells, it suggests that the persistent or late current would eg be smaller. Peak I Ca was found to be significantly smaller in neonate ventricular cells compared to adult cells Figure 9C. Several functions may not work. The reduced repolarization reserve due to the absence of I to and I Ks would suggest that the neonate heart would be more susceptible to arrhythmias following application of either an I Kr or I Ks blocker Figure 1.


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What if any is the exact error you are getting? Fedida D, Giles WR. Although cell size is very small at this stage of development, our u2521 to directly measure I Kr and I Ks in neonate cells yielded unequivocal results.

Acta Physiol Oxf ; Our data confirm that the ventricular myocardium in the 2 week old dog is homogeneous [ 26 ] and, therefore, we did not separate myocytes from the three distinct layers epi- mid- and endo- layers.

There are no conflicts of interest to disclose. Posted 22 February – Downloads View all categories Upload file New files since last visit Files from past 7 days. We next quantified peak I Ca elicited during application of h521 ms test pulse.

Characterization of the inward-rectifying potassium current in cat ventricular myocytes.

External solution contained in mM: Age-related appearance of outward currents may contribute to developmental differences in ventricular repolarization. In the canine myocardium it is believed that I to begins to develop 2 months after birth [ 8 ]. h25521

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ICa was greatly augmented, although I Ks was still absent. If so, human neonatal ventricular myocardium may be more susceptible to the development of arrhythmias following a further inward shift in the balance of current secondary to ion channel mutations, particularly those causing a major gain of function of sodium channel current.


Recent studies suggest that approximately 1 out of 5 SIDS case h25211 be due ion channel variations [ 2 ]. Induction and removal of inward-going rectification in sheep cardiac Purkinje fibres.

In several experiments, the identity of the tail current was confirmed by addition of the I Kr specific blocker, E Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private g2521, post status updates, manage your profile and so much more.

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We next measured late I Na during a ms test pulse. Analysis of inward I Na and I Ca also showed these currents were significantly smaller compared to adult cells. A subpopulation of cells with unique electrophysiological properties in the deep subepicardium of the canine ventricle. Look for any entries with Yellow Exclamation! By comparison, the outward component of I K1 in adult mid cells contributes Single myocytes isolated from the left ventricle of week old canine neonate h2251 were studied using patch-clamp techniques.

Functionally distinct sodium channels in ventricular epicardial and endocardial cells contribute to a greater sensitivity of the epicardium to electrical depression.