Biomaterial Database

Behavior of left ventricular mechanoreceptors with myelinated and nonmyelinated afferent vagal fibers in cats. 1983

B N Gupta, and M D Thames

The purpose of this study was to determine the behavior of left ventricular mechanoreceptors with myelinated vagal afferents and to compare them with endings with nonmyelinated vagal afferents. Single unit activity was recorded from 13 endings with nonmyelinated vagal afferents (conduction velocity 2.1 +/- 0.3 m/sec) and from 16 endings with myelinated vagal afferents (conduction velocity 7.3 +/- 1.3 m/sec). Resting discharge frequencies of nonmyelinated afferents and of myelinated vagal afferents were 1.7 +/- 0.3 and 2.7 +/- 0.5 imp/sec (P less than 0.1), respectively (at left ventricular end diastolic pressure of 6 mm Hg for both groups). Ten of 16 myelinated vagal afferents had pulse synchronous discharge under basal condition, whereas only 3 of 13 nonmyelinated vagal afferents had such activity. During aortic occlusion, the discharge of myelinated vagal afferents increased 1.7 +/- 0.3 imp/sec per mm Hg, whereas nonmyelinated vagal afferents increased significantly (P less than 0.05) less (0.5 +/- 0.1 imp/sec per mm Hg). Discharge for both groups was linearly related to left ventricular end-diastolic pressure but not to left ventricular systolic pressure. Increases in left ventricular systolic pressure alone did not increase firing for either group. During aortic occlusion, the maximum discharge rates of myelinated vagal afferents (43 +/- 7 imp/sec) were significantly higher than those of nonmyelinated vagal afferents (14 +/- 3 imp/sec) at left ventricular end-diastolic pressure of 30 +/- 2 and 24 +/- 2 mm Hg, respectively. Both groups increased their discharge during volume expansion with myelinated vagal afferents showing greater sensitivity than nonmyelinated vagal afferents. All endings studied were in the inferoposterior wall of the left ventricle. All nonmyelinated vagal afferents were in or near the epicardium. In contrast, myelinated vagal afferents were equally distributed between the endocardium and the epicardium. Myelinated vagal afferents had discrete receptive fields (1-2 mm2) whereas those of nonmyelinated vagal afferents were much larger (1 cm2). In conclusion, the discharge of left ventricular endings with nonmyelinated vagal afferents and myelinated vagal afferents both appear to be determined mainly by changes in left ventricular end-diastolic pressure. They may be located at different depths in the left ventricular wall. Myelinated vagal afferents have greater sensitivity and maximum firing frequencies than nonmyelinated vagal afferents.

UI	MeSH Term	Description	Entries
D008465	Mechanoreceptors	Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.	Golgi Tendon Organ,Golgi Tendon Organs,Krause's End Bulb,Krause's End Bulbs,Mechanoreceptor,Mechanoreceptor Cell,Meissner's Corpuscle,Neurotendinous Spindle,Neurotendinous Spindles,Receptors, Stretch,Ruffini's Corpuscle,Ruffini's Corpuscles,Stretch Receptor,Stretch Receptors,Mechanoreceptor Cells,Bulb, Krause's End,Bulbs, Krause's End,Cell, Mechanoreceptor,Cells, Mechanoreceptor,Corpuscle, Meissner's,Corpuscle, Ruffini's,Corpuscles, Ruffini's,End Bulb, Krause's,End Bulbs, Krause's,Krause End Bulb,Krause End Bulbs,Krauses End Bulb,Krauses End Bulbs,Meissner Corpuscle,Meissners Corpuscle,Organ, Golgi Tendon,Organs, Golgi Tendon,Receptor, Stretch,Ruffini Corpuscle,Ruffini Corpuscles,Ruffinis Corpuscle,Ruffinis Corpuscles,Spindle, Neurotendinous,Spindles, Neurotendinous,Tendon Organ, Golgi,Tendon Organs, Golgi
D009413	Nerve Fibers, Myelinated	A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.	A Fibers,B Fibers,Fiber, Myelinated Nerve,Fibers, Myelinated Nerve,Myelinated Nerve Fiber,Myelinated Nerve Fibers,Nerve Fiber, Myelinated
D009431	Neural Conduction	The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.	Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
D009475	Neurons, Afferent	Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.	Afferent Neurons,Afferent Neuron,Neuron, Afferent
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
D002306	Cardiac Volume	The volume of the HEART, usually relating to the volume of BLOOD contained within it at various periods of the cardiac cycle. The amount of blood ejected from a ventricle at each beat is STROKE VOLUME.	Heart Volume,Cardiac Volumes,Heart Volumes,Volume, Cardiac,Volume, Heart,Volumes, Cardiac,Volumes, Heart
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003250	Constriction	The act of constricting.	Clamping,Clampings,Constrictions
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
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