Biomaterial Database

Effects of calcium channel blockers on isolated carotid baroreceptors and baroreflex. 1983

C M Heesch, and B M Miller, and M D Thames, and F M Abboud

Our study determined the effects of the calcium antagonists, nifedipine and verapamil, on the carotid sinus baroreceptors and baroreflex. The left carotid sinus region in dogs was vascularly isolated and filled with oxygenated physiological salt solution. Steady-state multiunit activity was recorded from the carotid sinus nerve for sinus pressures of 50-200 mmHg after bathing the carotid sinus region in a solution containing no drug, 10 micrograms/ml nifedipine (n = 6), or 5 micrograms/ml verapamil (n = 5). The slopes of the curves relating carotid sinus nerve activity (% of maximum control) to carotid sinus pressure were control, 0.81 +/- 0.06; nifedipine, 1.29 +/- 0.14; and verapamil, 0.48 +/- 0.06%/mmHg, indicating that nifedipine increased and verapamil decreased the sensitivity of the carotid sinus baroreceptors. Additional studies with bilateral carotid sinus isolation (carotid sinus nerves intact) indicated that nifedipine enhanced and verapamil attenuated carotid baroreflex control of renal sympathetic nerve activity. Pressure-volume curves generated in the isolated carotid sinus showed that effects on smooth muscle do not account for the opposing effects of the two Ca2+ antagonists. Omitting Ca2+ from the physiological solution resulted in increased carotid sinus nerve activity, an effect blocked by verapamil but not nifedipine. Verapamil, but not nifedipine, inhibited veratrine-induced (Na+-dependent) excitation of carotid baroreceptors. Thus the excitatory effects of nifedipine on the carotid sinus baroreceptors are dependent on Ca2+ mechanisms, whereas the inhibitory effects of verapamil may be due mainly to interference with the inward Na+ current.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D009543	Nifedipine	A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.	Adalat,BAY-a-1040,Bay-1040,Cordipin,Cordipine,Corinfar,Fenigidin,Korinfar,Nifangin,Nifedipine Monohydrochloride,Nifedipine-GTIS,Procardia,Procardia XL,Vascard,BAY a 1040,BAYa1040,Bay 1040,Bay1040,Monohydrochloride, Nifedipine,Nifedipine GTIS
D011311	Pressoreceptors	Receptors in the vascular system, particularly the aorta and carotid sinus, which are sensitive to stretch of the vessel walls.	Baroreceptors,Receptors, Stretch, Arterial,Receptors, Stretch, Vascular,Stretch Receptors, Arterial,Stretch Receptors, Vascular,Arterial Stretch Receptor,Arterial Stretch Receptors,Baroreceptor,Pressoreceptor,Receptor, Arterial Stretch,Receptor, Vascular Stretch,Receptors, Arterial Stretch,Receptors, Vascular Stretch,Stretch Receptor, Arterial,Stretch Receptor, Vascular,Vascular Stretch Receptor,Vascular Stretch Receptors
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
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
D002339	Carotid Arteries	Either of the two principal arteries on both sides of the neck that supply blood to the head and neck; each divides into two branches, the internal carotid artery and the external carotid artery.	Arteries, Carotid,Artery, Carotid,Carotid Artery
D002346	Carotid Sinus	The dilated portion of the common carotid artery at its bifurcation into external and internal carotids. It contains baroreceptors which, when stimulated, cause slowing of the heart, vasodilatation, and a fall in blood pressure.	Sinus, Carotid