Biomaterial Database

Angiotensin II decreases spontaneous firing rate of guinea-pig sino-atrial node cells. 2011

Jing-Wei Sheng, and Wen-Ying Wang, and Yan-Fang Xu

Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.

Angiotensin II (Ang II) plays an important role in the regulation of cardiac function, but its electrophysiological effects on sino-atrial (SA) node are not well understood. In this study, the immediate effect of Ang II on action potentials and ionic currents were investigated by using whole-cell patch-clamps in single guinea-pig SA node pacemaker cells. We demonstrated that Ang II exerted a negative effect on spontaneous firing rate, with a concomitant reduction in the slope of diastolic depolarization. The inhibitory effect of Ang II on spontaneous activity displayed a concentration-dependent manner in the range of 1-1000 nM, with IC50 of 8.34 nM. Ang II type 1 (AT1) receptor antagonist valsartan (1 μM) abolished the inhibitory effect. In contrast, Ang II type 2 (AT2) receptor antagonist, PD123319 (1 μM) didn't affect the action of Ang II. Ang II had no significant effect on hyperpolarization-activated current (If) in SA node cells. However, it significantly slowed the deactivation of the slowly activated delayed rectifier K+ current (Iks) and increased the tail current density. Furthermore, Ang II decreased the current density of L-type Ca2+ current in SA node cells. Our data demonstrate that Ang II reduces the auto rhythm of SA node cells via enhancing Iks and reducing ICaL. The result suggests a potential mechanism by which elevated levels of Ang II may be involved in the occurrence of SA node dysfunction in cardiac pathophysiology.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000804	Angiotensin II	An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the C-terminal by ANGIOTENSIN CONVERTING ENZYME. The amino acid in position 5 varies in different species. To block VASOCONSTRICTION and HYPERTENSION effect of angiotensin II, patients are often treated with ACE INHIBITORS or with ANGIOTENSIN II TYPE 1 RECEPTOR BLOCKERS.	Angiotensin II, Ile(5)-,Angiotensin II, Val(5)-,5-L-Isoleucine Angiotensin II,ANG-(1-8)Octapeptide,Angiotensin II, Isoleucine(5)-,Angiotensin II, Valine(5)-,Angiotensin-(1-8) Octapeptide,Isoleucine(5)-Angiotensin,Isoleucyl(5)-Angiotensin II,Valyl(5)-Angiotensin II,5 L Isoleucine Angiotensin II,Angiotensin II, 5-L-Isoleucine
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012849	Sinoatrial Node	The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).	Sinuatrial Node,Sinus Node,Sino-Atrial Node,Sinu-Atrial Node,Node, Sino-Atrial,Node, Sinoatrial,Node, Sinu-Atrial,Node, Sinuatrial,Node, Sinus,Nodes, Sino-Atrial,Nodes, Sinoatrial,Nodes, Sinu-Atrial,Nodes, Sinuatrial,Nodes, Sinus,Sino Atrial Node,Sino-Atrial Nodes,Sinoatrial Nodes,Sinu Atrial Node,Sinu-Atrial Nodes,Sinuatrial Nodes,Sinus Nodes
D020746	Calcium Channels, L-Type	Long-lasting voltage-gated CALCIUM CHANNELS found in both excitable and non-excitable tissue. They are responsible for normal myocardial and vascular smooth muscle contractility. Five subunits (alpha-1, alpha-2, beta, gamma, and delta) make up the L-type channel. The alpha-1 subunit is the binding site for calcium-based antagonists. Dihydropyridine-based calcium antagonists are used as markers for these binding sites.	Dihydropyridine Receptors,L-Type Calcium Channels,L-Type VDCC alpha-1 Subunit,L-Type Voltage-Dependent Calcium Channel,Long-Lasting Calcium Channel,Long-Lasting Calcium Channels,Receptors, Dihydropyridine,Dihydropyridine Receptor,L-Type Calcium Channel,L-Type VDCC,L-Type VDCC alpha-2 Subunit,L-Type VDCC beta Subunit,L-Type VDCC delta Subunit,L-Type VDCC gamma Subunit,L-Type Voltage-Dependent Calcium Channels,Calcium Channel, L-Type,Calcium Channel, Long-Lasting,Calcium Channels, L Type,Calcium Channels, Long-Lasting,Channel, Long-Lasting Calcium,L Type Calcium Channel,L Type Calcium Channels,L Type VDCC,L Type VDCC alpha 1 Subunit,L Type VDCC alpha 2 Subunit,L Type VDCC beta Subunit,L Type VDCC delta Subunit,L Type VDCC gamma Subunit,L Type Voltage Dependent Calcium Channel,L Type Voltage Dependent Calcium Channels,Long Lasting Calcium Channel,Long Lasting Calcium Channels,Receptor, Dihydropyridine,VDCC, L-Type
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In