Contractility and the Length-Tension Relation of the Dog Anterior Tibial Artery

Price, J. M.; Davis, Darrell L.

doi:10.1159/000158340

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…However, smooth muscle lacks the rather clear relationship between ultrastructural organization and length-dependent contractile phenomena that is characteristic of skeletal muscle, and an important area of current investigation in smooth muscle mechanics is the search for the cellular basis of the length-dependent function of smooth muscle (203,239,247,282). Some recent work indicates that, as is the case for skeletal muscle (43,44,188) and cardiac muscle (149,159,184), the degree of activation of smooth muscle is affected by its length; the level of activation decreases as the muscle length decreases (239, [251][252][253]282).…”

Section: Isometric Mechanical Behaviormentioning

confidence: 99%

Mechanical properties of gastrointestinal smooth muscle

Meiss

1989

Comprehensive Physiology

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Section: Isometric Mechanical Behaviormentioning

confidence: 99%

Mechanical properties of gastrointestinal smooth muscle

Meiss

1989

Comprehensive Physiology

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“…Force was mea sured by a Statham UC2 force transducer [28], The transducer was calibrated before each experiment with known weights.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Length-Tension Properties of the Anterior Tibial Artery in Normotensive and Perinephritic Hypertensive Dogs

Price¹,

Davis²,

Baker³

1982

J Vasc Res

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The length-active tension relation has been previously reported to be decreased or unchanged in hypertensive vessels whereas resting distensibility was unchanged or increased. We found the maximum active stress and the internal ring circumference, in millimeters, at which it occurs (Lmax) to be lower in arterial rings from perinephritic hypertensive dogs than in rings from normotensive dogs. The internal circumferences (length) at which resting force and active force became zero (L₀ and Lmin, respectively) were unchanged. Lmax, L₀ and Lmin were used to normalize length-tension diagrams. Active stress was significantly lower in hypertensive vessels at most of the lengths tested with the diagram normalized to Lmax· When the length-tension diagram was normalized to Lmin there was no difference in the active stress at any of the lengths tested. The length-resting stress curves were identical when the diagram was normalized to Lmax but the curve for hypertensive vessels was higher when the diagram was normalized to L₀. An important characteristic of these length-tension curves is that normalized lengths correspond to the same absolute length in each group of vessels when the reference length has the same absolute value (L₀ and Lmin in this study). This separates differences due to absolute length from differences associated with hypertension. We conclude that perinephritic hypertension in the dog is accompanied by a decrease in resting distensibility of the arterial wall. The results indicate that the choice of reference length may affect the values of stress and tension that are obtained for comparison of length-tension relationships in hypertensive and normotensive blood vessels.

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Length-dependent activation and sensitivity in arterial ring segments

Price

1984

Ann Biomed Eng

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This study examines the effect of length on the dose-response (D-R) relationship and the effect of agonist concentration on the length-tension (L-T) relationship in vascular smooth muscle. The experiments used 2-mm rings from isolated segments of the dog anterior tibial artery. In D-R experiments the length (internal ring circumference) for maximum active force (Lmax) was determined first. D-R relationships were obtained from cumulative responses to increasing concentrations of norepinephrine (NE) or potassium (K+). L-T relationships were obtained from individual responses to a specific concentration of agonist as the ring was stretched in increments of L0 (the initial length for resting force). Dimensions of the arterial rings were measured with a video caliper. For NE and K+ stimulations at lengths equal to and less than Lmax: (a) The concentration for half maximal response (ED50) was lowest (most sensitive) at Lmax and increased significantly as length decreased from Lmax; (b) When the direction of length change was reversed, the direction of change in ED50 was reversed; and (c) The ED50 of repeated dose-response experiments at Lmax was not significantly different. For NE: (a) the ED50 decreased significantly when length was decreased to Lmax. The results of L-T experiments show Lmax is significantly longer for a low concentration of NE (10(-6) M) than for a high concentration (10(-5) M). With force normalized to the maximum force, the L-T curve is significantly lower, and the initial length for an active response was 80% longer for 10(-6) M than for 10(-5) M NE. It may be concluded that vascular smooth muscle has a length-dependent dose-response relationship and a concentration-dependent length-tension relationship.

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Contractility and the Length-Tension Relation of the Dog Anterior Tibial Artery

Cited by 3 publications

References 18 publications

Mechanical properties of gastrointestinal smooth muscle

Mechanical properties of gastrointestinal smooth muscle

Length-Tension Properties of the Anterior Tibial Artery in Normotensive and Perinephritic Hypertensive Dogs

Length-dependent activation and sensitivity in arterial ring segments

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