The α1-adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the frequency of spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nM) much more potently than activation by phenylephrine adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the frequency of spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nM) much more potently than activation by phenylephrine adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the frequency of spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nM) much more potently than activation by phenylephrine adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the frequency of spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nM) much more potently than activation by phenylephrine adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the frequency of spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nM) much more potently than activation by phenylephrine adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the frequency of spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nM) much more potently than activation by phenylephrine adrenergic receptors are Gq protein-coupled receptors that play a key role in the modulation of sympathetic nervous system activity and are the site of action for therapeutic agents, such as antihypertensive drugs. A-61603 is a selective α1A-adrenergic receptor agonist that is at least 35-fold more potent at α1A receptor sites than at α1B or α1D. Activation of the α1A-adrenergic receptor by A-61603 has been reported to increase the