In vivo acceleration of heart relaxation performance by parvalbumin gene delivery

Abstract

Defective cardiac muscle relaxation plays a causal role in heart failure. Shown here is the new in vivo application of parvalbumin, a calcium-binding protein that facilitates ultrafast relaxation of specialized skeletal muscles. Parvalbumin is not naturally expressed in the heart. We show that parvalbumin gene transfer to the heart in vivo produces levels of parvalbumin characteristic of fast skeletal muscles, causes a physiologically relevant acceleration of heart relaxation performance in normal hearts, and enhances relaxation performance in an animal model of slowed cardiac muscle relaxation. Parvalbumin may offer the unique potential to correct defective relaxation in energetically compromised failing hearts because the relaxation-enhancement effect of parvalbumin arises from an ATP-independent mechanism. Additionally, parvalbumin gene transfer may provide a new therapeutic approach to correct cellular disturbances in calcium signaling pathways that cause abnormal growth or damage in the heart or other organs.J. Clin. Invest. 107:191-198 (2001).questions: (a) Could physiologically relevant levels of parvalbumin be achieved in the left ventricle at 6 days after gene transfer? (b) Under physiological conditions, can parvalbumin alter mechanical relaxation properties of the left ventricle? (c) Can parvalbumin improve heart performance in an experimental model of abnormally slow myocardial relaxation? MethodsCardiac gene transfer in vivo. Adult, female Sprague-Dawley rats (250 g) were anesthetized with sodium pentobarbital (30 mg/kg body weight intraperitoneally). Animals were intubated and placed on artificial ventilation (50-60 breaths per minute). A thoracotomy was performed over the third intercostal space of the left thorax to expose the heart. An insulin syringe was inserted into the LV free wall (apical to base), using the left anterior descending coronary artery as a guide, and then slowly injecting 50-100 µl solution (parvalbumin titer, 1.87 × 10 10 PFU/ml; AdlacZ titer, 1.00 × 10 10 PFU/ml, each in PBS/10% glycerol; vehicle was PBS/10% glycerol) while withdrawing the syringe. The chest was closed and negative pleural pressure reestablished before extubation. Animals were given antibiotics via the drinking water. At day 6 after gene (or vehicle) transfer, heart parvalbumin expression and/or heart mechanical function was evaluated. This procedure has been approved by the University Committee on the Use and Care of Animals at the University of Michigan.Myocardial relaxation performance. At day 6 after gene transfer, hearts were isolated, retrogradely perfused with oxygenated Krebs-Henseleit buffer warmed to 37°C, and electrically paced at 4 Hz (supramaximal, 5-millisecond pulses; Model S5 Stimulator; Grass Instruments, Quincy, Massachusetts, USA). Cardiac twitch contractile parameters (see Figure 3) were obtained from Langendorff perfused hearts by placing monofilament sutures at the apical and the base regions of the LV wall (between the circumflex and lateral descending coronary arteries). The base sutu...

Gene Transfer of Parvalbumin Improves Diastolic Dysfunction in Senescent Myocytes

“…Further confirmation of the ability of parvalbumin to restore diastolic parameters to normal was obtained in an in vivo setting, in which injection of parvalbumin into the LV free wall both accelerated myocardial relaxation under physiological conditions and improved myocardial twitch relaxation rates and ϪdP/dt in hypothyroid hearts to normal. 10 In this study, we demonstrate that adenoviral gene transfer of parvalbumin, a protein affecting solely the lusitropic properties of myocardium, can be used to successfully transduce senescent myocytes and significantly improves myocardial relaxation in healthy senescent cardiac myocytes. The calcium transient decay rate is significantly improved in senescent parvalbumin-transduced myocytes compared with GFP-expressing and control myocytes, and the time from peak to 50% calcium in senescent myocytes transduced with parvalbumin is comparable to that of adult controls.…”

“…9 Adenoviral transduction of parvalbumin into the LV free wall has been shown to significantly accelerate LV isovolumic relaxation times in normal animals and also to restore normal relaxation performance in hypothyroidisminduced diastolic dysfunction. 10 In addition, adenoviral gene transfer of parvalbumin into adult myocytes in vitro has been shown to significantly increase the rate of myocyte relaxation (ϪdL/dT max , t 1/2R ) and to decrease the rate of decay of the intracellular calcium transient. Not only were relaxation parameters in normal adult myocytes improved, but also, in hypothyroid animals, parvalbumin gene delivery fully corrected diastolic dysfunction by improving myocyte relaxation to levels seen in control animals.…”

Cytosolic Ca2+ Buffers

“…Conversely, the overexpression of PV by injection of Pvalb cDNA into the rat slow-twitch muscle, soleus, significantly increases the speed of relaxation, without affecting the contraction (Muntener et al 1995). Pvalb gene delivery in rat heart in vivo increases the rate of heart relaxation in normal hearts and in an animal model of slowed cardiac muscle relaxation (Szatkowski et al 2001). Thus, PV or genetically "tuned" PV variants are discussed as potential tools to enhance cardiac diastolic function (Rodenbaugh et al 2007;Wang and Metzger 2008).…”

Obesity and Hypertension-Induced Restrictive Cardiomyopathy

“…For instance, the gene for parvalbumin was expressed in the hearts of Sprague-Dawley rats. 17 The protein's presence was verified by immunofluorescence. The investigators demonstrated a substantial increase in diastolic relaxation.…”