Biomaterial Database

Effects of calcium channel agonism by Bay-K-8644 on ventricular fibrillation threshold of isolated heart. 1992

M G Worthington, and L H Opie

Ischaemic Heart Disease Research Unit of the Medical Research Council, Cape Town, South Africa.

The hypothesis tested was that enhanced entry of calcium into cardiac cells would increase the susceptibility to ventricular fibrillation as measured by the ventricular fibrillation threshold (VFT) of the isolated perfused rat heart. Bay-K-8644 was used as a calcium-channel agonist. There was a biphasic effect with a maximal increase in left ventricular systolic pressure and oxygen uptake at a concentration of 10(-7) M. The same concentration caused a major reduction in the VFT. The bell-shaped pattern of fall of the VFT was inversely related to the effect on LV developed pressure. The changes in VFT could be dissociated from those on myocardial metabolites. Although Bay-K-8644 increased the heart rate, reduction of the VFT could also be obtained in paced hearts. The addition of ryanodine, an agent known to interrupt intracellular recycling of calcium through the sarcoplasmic reticulum, was able to abolish approximately half the effect of Bay-K-8644 on the VFT. Therefore, increased entry of calcium via the calcium channel is able to reduce VFT, acting in part through enhanced recycling of calcium through the sarcoplasmic reticulum.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002304	Cardiac Pacing, Artificial	Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.	Pacing, Cardiac, Artificial,Artificial Cardiac Pacing,Artificial Cardiac Pacings,Cardiac Pacings, Artificial,Pacing, Artificial Cardiac,Pacings, Artificial Cardiac
D003326	Coronary Circulation	The circulation of blood through the CORONARY VESSELS of the HEART.	Circulation, Coronary
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D000242	Cyclic AMP	An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.	Adenosine Cyclic 3',5'-Monophosphate,Adenosine Cyclic 3,5 Monophosphate,Adenosine Cyclic Monophosphate,Adenosine Cyclic-3',5'-Monophosphate,Cyclic AMP, (R)-Isomer,Cyclic AMP, Disodium Salt,Cyclic AMP, Monoammonium Salt,Cyclic AMP, Monopotassium Salt,Cyclic AMP, Monosodium Salt,Cyclic AMP, Sodium Salt,3',5'-Monophosphate, Adenosine Cyclic,AMP, Cyclic,Adenosine Cyclic 3',5' Monophosphate,Cyclic 3',5'-Monophosphate, Adenosine,Cyclic Monophosphate, Adenosine,Cyclic-3',5'-Monophosphate, Adenosine,Monophosphate, Adenosine Cyclic