Biomaterial Database

Control of the myocardial contractile state by carotid chemo- and baroreceptor and pulmonary inflation reflexes in conscious dogs. 1978

S F Vatner, and J D Rutherford

The effects of carotid chemoreceptor stimulation with intracarotid injections of either nicotine, 0.2 mug/kg, or cyanide, 2 mug/kg, were compared with the effects of bilateral carotid occlusion on left ventricular (LV) pressure, dP/dt, and diameter in conscious dogs instrumented with ultrasonic diameter gauges and miniature pressure gauges. With heart rate maintained constant, carotid chemoreceptor stimulation increased mean arterial pressure by 27+/-3%, LV and diastolic diameter by 4+/-0.9% and LV dP/dt by 21+/-2%. With ventilation controlled during succinylcholine infusion, carotid chemoreceptor stimulation increased mean arterial pressure by 43+/-2% and dP/dt by 37+/-5%, values significantly greater, P < 0.01, than were observed in dogs with spontaneous ventilation. Similarly, in dogs with spontaneous ventilation after vagotomy, carotid chemoreceptor stimulation also increased dP/dt by a greater amount, i.e., by 48+/-9%. The increases in LV end diastolic diameter were not affected significantly by either cholinergic blockade with atropine or beta adrenergic blockade with propranolol. Although cholinergic blockade did not affect the inotropic or pressor responses significantly, beta adrenergic blockade attenuated the pressor response and essentially abolished the inotropic response. Bilateral carotid occlusion increased mean arterial pressure and LV end diastolic diameter by similar amounts to those observed with chemoreceptor stimulation, but increased dP/dt significantly less, P < 0.02, i.e., by 13+/-2%. As was observed with chemoreceptor stimulation, inotropic responses were not affected significantly by cholinergic blockade, but were essentially abolished by beta adrenergic blockade. Thus, in the conscious dog with heart rate constant, carotid chemoreceptor stimulation induces a clear positive inotropic effect, which is greater in the absence of the attenuating influences of pulmonary inflation reflexes, and for an equal elevation in arterial pressure appears to exert a greater increase in myocardial contractility than does carotid baro-receptor unloading.

UI	MeSH Term	Description	Entries
D008168	Lung	Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.	Lungs
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
D009538	Nicotine	Nicotine is highly toxic alkaloid. It is the prototypical agonist at nicotinic cholinergic receptors where it dramatically stimulates neurons and ultimately blocks synaptic transmission. Nicotine is also important medically because of its presence in tobacco smoke.	Nicotine Bitartrate,Nicotine Tartrate
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
D011433	Propranolol	A widely used non-cardioselective beta-adrenergic antagonist. Propranolol has been used for MYOCARDIAL INFARCTION; ARRHYTHMIA; ANGINA PECTORIS; HYPERTENSION; HYPERTHYROIDISM; MIGRAINE; PHEOCHROMOCYTOMA; and ANXIETY but adverse effects instigate replacement by newer drugs.	Dexpropranolol,AY-20694,Anaprilin,Anapriline,Avlocardyl,Betadren,Dociton,Inderal,Obsidan,Obzidan,Propanolol,Propranolol Hydrochloride,Rexigen,AY 20694,AY20694,Hydrochloride, Propranolol
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.
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
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
D002628	Chemoreceptor Cells	Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.	Chemoreceptive Cells,Cell, Chemoreceptive,Cell, Chemoreceptor,Cells, Chemoreceptive,Cells, Chemoreceptor,Chemoreceptive Cell,Chemoreceptor Cell
D003486	Cyanides	Inorganic salts of HYDROGEN CYANIDE containing the -CN radical. The concept also includes isocyanides. It is distinguished from NITRILES, which denotes organic compounds containing the -CN radical.	Cyanide,Isocyanide,Isocyanides