Biomaterial Database

Smooth muscle tone and rapid resetting of rat aortic baroreceptors. 1992

M C Andresen, and M Yang

Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550.

Changes in conditioning mean arterial pressure (cMAP) selectively alter the set point of arterial baroreceptors and baroreflexes without affecting gain. Changes in smooth muscle tone at constant cMAPs shift the pressure-discharge curves of aortic baroreceptors in a similar manner. Using an in vitro preparation of the rat aortic arch, we tested whether near maximal changes in smooth muscle tone affect rapid resetting in single regularly discharging aortic baroreceptors. Discharge, pressure, and aortic diameter were simultaneously measured. By using vasoactive drugs (phenylephrine, angiotensin II, Bay K 8644, and nitroprusside), rapid resetting to cMAP changes was tested during different smooth muscle tone conditions (control, constricted, and dilated). Baroreceptor discharge-response curves were periodically assessed with slow ramps of increasing pressure at each of three different cMAP levels (10-15 minutes each). Rapid resetting relations were constructed for pressure threshold (Pth) and diameter threshold (Dth) plotted against cMAP and conditioning diameter (cD), respectively. Vasoconstriction decreased Pth in all baroreceptors (n = 13, p less than 0.05). Baroreceptor resetting ability as indicated by the slopes of the resetting relations (pressure- or diameter-resetting ratios, delta Pth/delta cMAP or delta Dth/delta cD, respectively) was unaffected by large increases in smooth muscle tone (p greater than 0.12). Vasoconstriction, however, offset the pressure-resetting relation, shifting the linear relation in a parallel manner to higher Pth values. In contrast, Dth values during vasoconstriction were not offset but instead fell along a single diameter-resetting relation coincident with the control relation for each baroreceptor. This last result suggests that acute alteration of vessel mechanics by vasoconstriction does not alter the basic rapid resetting process.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009129	Muscle Tonus	The state of activity or tension of a muscle beyond that related to its physical properties, that is, its active resistance to stretch. In skeletal muscle, tonus is dependent upon efferent innervation. (Stedman, 25th ed)	Muscle Tension,Muscle Tightness,Muscular Tension,Tension, Muscle,Tension, Muscular,Tightness, Muscle,Tonus, Muscle
D009131	Muscle, Smooth, Vascular	The nonstriated involuntary muscle tissue of blood vessels.	Vascular Smooth Muscle,Muscle, Vascular Smooth,Muscles, Vascular Smooth,Smooth Muscle, Vascular,Smooth Muscles, Vascular,Vascular Smooth Muscles
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
D011919	Rats, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.	August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
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
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
D001011	Aorta	The main trunk of the systemic arteries.	Aortas
D014661	Vasoconstriction	The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.	Vasoconstrictions
D014662	Vasoconstrictor Agents	Drugs used to cause constriction of the blood vessels.	Vasoactive Agonist,Vasoactive Agonists,Vasoconstrictor,Vasoconstrictor Agent,Vasoconstrictor Drug,Vasopressor Agent,Vasopressor Agents,Vasoconstrictor Drugs,Vasoconstrictors,Agent, Vasoconstrictor,Agent, Vasopressor,Agents, Vasoconstrictor,Agents, Vasopressor,Agonist, Vasoactive,Agonists, Vasoactive,Drug, Vasoconstrictor,Drugs, Vasoconstrictor