Long-Term IL-2 Incubation-Induced L-type Calcium Channels Activation in Rat Ventricle Cardiomyocytes

Abstract

The following study examined the impact of IL-2 on Ca channel activity in the event of several hours' incubation in IL-2. The right ventricle free wall for action potential measurements was isolated and perfused with Tyrode solution. The whole-cell voltage clamp experiments were performed on enzymatically isolated single cardiomyocytes. The whole-cell voltage clamp recording of Ca currents was performed using the Cs-based pipette and bath solutions. The protocol with depolarizing prepulse (- 40 mV) was used to inactivate both Na current and Ca T-type current. The L-type Ca current was elicited by a series of 250 ms depolarizing square pulses with 10 mV increments. At the 15th minute of continuous recording, the peak density at 0 mV was - 3.036 ± 0.3015 pA/pF under IL-2 and - 3.008 ± 0.3452 pA/pF in control conditions. The IL-2 in moderate concentration (1 ng/mL) has no acute effects on I in rat ventricular cells. In contrast, to the lack of acute effects, the long-term incubation with IL-2 (2 h or more) produced a prominent enhancement of Ca L-type current. In rat, ventricular myocardium IL-2 (1 ng/mL) produced a very gradual prolongation of subendocardial APs which reached a maximal extent after 3-4 h of treatment. The patch clamp study shows an IL-2-induced I current activation, while the action potential studies on multicellular ventricular preparations suggest an IL-2-induced L-type Ca channel participation in the development of AP.

Cardiomyocytes' prolonged IL‐2 incubation induces enhancement in L‐type Ca2+ channels mediated by inhibitory‐kappaB kinase/nuclear factor‐kappaB signalling

“…First and foremost, a brief backup was performed of the studied L‐type Ca 2+ currents expressed in the ventricular cardiomyocytes. Summarily, the recorded L‐type Ca 2+ currents had a maximum peak density at 0 mV and were sensitive to nifedipine (10 μmol/L) (Figure 1Ab, ii‐ inset ) (for details, see also Filatova et al 2019) 5 . After 2 hours of incubation in IL‐2, the current at 0 mV was approximately 100% higher than at the start of the incubation (n = 9, P < .001, Figure 1A,B).…”

“…The principle of isolation of cardiomyocytes was described in previous works of this research group 5,17 . Briefly, the hearts were attached to the Langendorff apparatus for retrograde perfusion with Ca 2+ ‐free solution containing (in mmol/L) NaCl 120, KCl 5.4, MgSO 4 x7H 2 O 5, Na‐pyruvate 5, glucose 20, taurine 20 and Hepes 10 at a pH of 7.4 adjusted with NaOH.…”

“…In this experimental set‐up, whole‐cell voltage‐clamp recordings were performed on single cells. Electrophysiological adjustments, solutions, and patch pipette specifications were given in detail in the previous study 5 . Briefly, after isolation, myocytes (in small aliquots) were placed in an open perfusion chamber and allowed to adhere to the bottom of the chamber for 10‐15 minutes.…”

“…Briefly, after isolation, myocytes (in small aliquots) were placed in an open perfusion chamber and allowed to adhere to the bottom of the chamber for 10‐15 minutes. The caesium (Cs + )‐based solution was used for measurement of the L‐type Ca 2+ currents ( I Ca,L ) and had the same composition as the Kraftbrühe medium, with the exception of the KCl, which was replaced by equimolar CsCl 5 . 4‐Aminopyridine (4‐AP), (2 mmol/L) was added to the solution to eliminate K + currents ( I to and I Kur ).…”

“…4 Conversely, there is a direct relation between [Ca 2+ ] i and function of the L-type Ca 2+ channels, in which this study has shown are targeted by prolonged incubation in IL-2. 5 However, apart from this effect, there is no information on whether the prolonged effect of IL-2 alters some specific inflammatory pathways in the myocardium. One of these specific inflammatory pathways could…”