What question did this study set out to answer?

To determine whether vascular smooth muscle sensitivity to norepinephrine continues to increase at muscle lengths greater than the length required for maximum active force generation.

September 1, 1983AJP Heart and Circulatory Physiology

Length-dependent sensitivity at lengths greater than Lmax in vascular smooth muscle

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To determine whether vascular smooth muscle sensitivity to norepinephrine continues to increase at muscle lengths greater than the length required for maximum active force generation.
Measured dose-response curves for norepinephrine in canine anterior tibial artery rings across lengths ranging from below to above Lmax (0.70 Lmax, 1.00 Lmax, 1.15 Lmax, and 1.30 Lmax).
Calculated agonist concentration for half-maximal response (ED50) using graphical estimation and best-fit curve mathematical modeling.
Stretching arterial rings from Lmax to 1.15 Lmax and then to 1.30 Lmax significantly decreased the ED50 at each step, while shortening from 1.15 Lmax to 1.00 Lmax significantly increased ED50.
Stretching from 0.70 Lmax through Lmax to 1.30 Lmax caused a continuous, significant decrease in ED50, demonstrating that sensitivity increases progressively with length without plateauing at Lmax.
Active stress was significantly higher at Lmax than at 0.70 or 1.30 Lmax for norepinephrine concentrations above the Lmax ED50, but active stress was highest at 1.30 Lmax at sub-ED50 concentrations.

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Implication

Experimental study reveals continuous length-dependent sensitivity increases in canine arterial rings, suggesting smooth muscle sensitivity does not peak at optimal active force length.

Cite This Study

Price et al. (1983) studied this question.

synapsesocial.com/papers/6a8443a085a95bb87468cbb1 https://doi.org/10.1152/ajpheart.1983.245.3.h379

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Implication

Experimental study reveals continuous length-dependent sensitivity increases in canine arterial rings, suggesting smooth muscle sensitivity does not peak at optimal active force length.

Length-dependent sensitivity at lengths greater than Lmax in vascular smooth muscle

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Implication

Cite This Study

Length-dependent sensitivity at lengths greater than Lmax in vascular smooth muscle

Key Points

Discussion

Implication

Cite This Study

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