A Myocardial Slice Culture Model Reveals Alpha-1A-Adrenergic Receptor Signaling in the Human Heart

Abstract

Background Translation of preclinical findings could benefit from a simple, reproducible, high throughput human model to study myocardial signaling. Alpha-1A-adrenergic receptors (ARs) are expressed at very low levels in the human heart, and it is unknown if they function. Objectives To develop a high throughput human myocardial slice culture model, and to test the hypothesis that alpha-1A- ARs are functional in the human heart. Methods Cores of LV free wall 8 mm diameter were taken from 52 hearts (18 failing and 34 nonfailing). Slices 250 μm thick were cut with a Krumdieck apparatus and cultured using a rotating incubation unit. Results About 60 slices were cut from each LV core, and a typical study could use 96 slices. Myocyte morphology was maintained, and diffusion into the slice center was rapid. Slice viability was stable for at least 3 days in culture by ATP and MTT assays. The beta-AR agonist isoproterenol stimulated phospholamban phosphorylation, and the alpha-1A-AR agonist A61603 stimulated ERK phosphorylation, with nanomolar EC50 values in slices from both failing and nonfailing hearts. Strips cut from the slices were used to quantify activation of contraction by isoproterenol, A61603, and phenylephrine. The slices supported transduction by adenovirus. Conclusions We have developed a simple, high throughput LV myocardial slice culture model to study signaling in the human heart. This model can be useful for translational studies, and we show for the first time that the alpha-1A-AR is functional in signaling and contraction in the human heart.

An Alpha-1A Adrenergic Receptor Agonist Prevents Acute Doxorubicin Cardiomyopathy in Male Mice

“…Besides this report, several lines of evidence support the translation of α1A-agonist cardioprotection to human HF. α1-ARs levels and regulation are similar in mouse and human heart [4], and A61603 activates protective ERK signaling in human LV myocardium ex vivo [11]. Although α1-AR levels represent roughly 10% of the AR population in non-diseased hearts, with β-ARs at 90%, β-AR down-regulation in HF increases the proportion of α1-ARs to nearly 25% [2,4,49].…”

“…Among the 3 α1-AR subtypes (α1A, α1B, and α1D), rodent and human myocytes have the α1A and α1B [4], and most data implicate the α1A in adaptive effects [5,6,7,8,9,10,11]. However, it is unknown if an α1A-AR agonist can treat ardiomyopathy in vivo.…”

The Alpha-1A Adrenergic Receptor in the Rabbit Heart

“…Evidence for an important role for α1-adrenergic receptors (ARs) in cardiac myocyte physiology has accumulated over several decades (reviewed in [ 1 , 2 , 3 ]), even though these receptors are much less abundant than β-ARs. Among the 3 α1-AR subtypes, A, B, and D, the α1A is of special interest, since this subtype can mediate adaptive and protective effects in mouse models [ 4 , 5 , 6 , 7 ], and can stimulate protective ERK signaling and contraction in human myocardium [ 8 ].…”

Selective inhibition of electrical conduction within the pulmonary veins by α1-adrenergic receptors activation in the Rat

“…The precise physiological role of α1-adrenergic receptors in PV cardiomyocytes is not fully understood but our previous observations allow us to consider the possibility of inhibiting the conduction of PV ectopic activity to the LA using a pharmacological approach. Moreover several studies showed that these receptors are present and functional in the human myocardium 10,11 suggesting that this strategy might be transposed to humans. This attractive prospect, led us to investigate the effects of the α1-adrenergic receptors activation on the electrical α1-adrenergic receptor activation selectively suppresses electrical activity within pulmonary veins.…”