Tetraethylammonium-induced phasic arterial constriction: temporal and spatial characteristics.
In vitro techniques were developed to characterize temporal, spatial, and mechanical characteristics of tetraethylammonium (TEA)-induced phasic contractile activity in pressurized perfused canine femoral artery segments. Power spectral analysis revealed TEA-induced phasic activity to be included in the bandwidth from 0.004 to 0.016 Hz. The level of intraluminal pressure did not influence frequency characteristics of this activity. Mean total tangential stress increased proportionately with intraluminal pressure, whereas both mean developed tangential stress and the strain index mean percent change of external diameter showed a plateau in the 80- to 120-mmHg pressure range. TEA-induced phasic activity propagated longitudinally in all arteries studied. The velocity of longitudinal propagation (V, cm/s) varied with intraluminal pressure in a nonlinear fashion with V = 0.79 +/- 0.05 at 40 mmHg, V = 0.72 +/- 0.05 at 80 mm Hg, and V = 0.85 +/- 0.05 at 120 mmHg. V was not affected by tetrodotoxin, and phasic activity was abolished by verapamil. Phasic activity showed a primary direction of propagation 81 +/- 7% of the time; however, this direction was variable in all arteries. Thus vascular smooth muscle activation by TEA, which has been proposed as a model for coronary artery spasm, produces propagated constrictor responses in the ultra-low-frequency band with pressure-sensitive velocity characteristics and mechanical properties that are optimized in the physiological pressure range.
D000818:Animals; D004285:Dogs; D005263:Femoral Artery / Q000187:drug effects*; D010827:Physiology / Q000295:instrumentation; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*; D013997:Time Factors; D014661:Vasoconstriction; D014700:Verapamil / Q000494:pharmacology
D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D014700:Verapamil