Maturational Changes in the Pharmacological Characteristics and Actomyosin Content of Canine Arterial and Venous Tissue

Abstract

ABSTRACT. The purpose of this study was to compare indicating intervessel heterogeneity in maturation. (Pediatr the pharmacological characteristics and actomyosin conRes 21: 152-158, 1987) tent of arterial and venous tissue at different times during Abbreviations development. Rings of arteries (femoral, renal, carotid, pulmonary) and veins (saphenous, pulmonary, jugular) PSS, physiological salt solution were obtained from 1 wk, 1 month, and adult dogs, mounted li, initial length at their optimal length for force development and the KCl, potassium chloride contractile response to potassium chloride and phenyleph-L, optimal length rine determined. The strain at optimal length was less at PE, phenylephrine all ages in pulmonary artery and pulmonary and jugular ED50, concentration that produces half maximum response veins than in other vessels. All vessels exhibited an in-SDS, sodium dodecyl sulfate crease in maximum contractile response with development but the increase was greater for phenylephrine. In general, the magnitude of the maximum response of the jugular and pulmonary veins and pulmonary artery was less than other vessels at all ages. The sensitivity (half maximum reIt has been demonstrated by several investigators (1-5) that sponse) either increased or was unchanged in arteries with the mechanical responsiveness of arterial tissue to constrictor development, while in the veins it either decreased or was and dilator agents changes during the development of the animal unchanged. The relaxant effects of verapamil and isopro-(for more complete reviews see References 6 and 7). In general, terenol were determined on potassium chloride contracted the maximum response to constrictor agents increases while the vessels. Arterial tissue was minimally responsive to isopro-sensitivity (ED50) either does not change or increases. The terenol at all ages while venous tissue either increased its particular alteration in sensitivity observed may depend on the responsiveness (saphenous, pulmonary) with development constrictor agent used, the age range studied, or the animal or remained highly responsive (jugular). Verapamil, unlike species from which the vessel was obtained. Work from this isoproterenol, was an effective relaxant of all vessels. The laboratory (8) suggests that the increase in maximum contractile actomyosin content (mglmm) of femoral and renal arteries response that occurs in developing rat aorta between the ages of and saphenous and jugular veins increased with develop-1 and 2 months can be explained in part by an increase in the ment but this increase was accompanied by a parallel actomyosin content of the vessel; however, changes in maximum increase in total protein so that the ratio (actomyosinltotal contractile response occumng earlier (5) or later (8) are not due protein) was unchanged. In jugular veins from adult dogs to changes in contractile protein content. this ratio was smaller than in arterial tissue. In general, itThe response to vasodilator agents that operate via the P can be concluded th...

Developmental Changes in Thickness, Contractility, and Hypoxic Sensitivity of Newborn Lamb Cerebral Arteries

“…Thus, force per unit area either increased or did not change, suggesting that during maturation of cerebral arteries, synthesis of new collagen and elastin is not as important as development of the contractile apparatus. Although the present data do not enable differentiation between the mechanisms mediating this improvement in contractile capacity, other studies suggest that age-related .increases in actomyosin content and calcium-binding capacity may be involved (13,14).…”

Response to Calcium of Skinned Gallbladder Smooth Muscle from Newborn and Adult Guinea Pigs

“…For most smooth muscle tissues, the increased force can be demonstrated regardless of the agonist used. This has lead to the hypothesis that the increase in force that develops during the postnatal period is a complex process that involves factors specific to the mechanism of action of the agonist as well as factors independent of the agonist (9,(12)(13)(14).…”

“…This study did not address the factors that may be responsible for the observed difference in response to calcium. However, it has recently been suggested that the postnatal maturation of force development in vascular smooth muscle is associated with changes in contractile protein content and type and with changes in the concentration of calmodulin and its sensitivity to activation by calcium (12,18). It will be interesting to determine if similar biochemical differences exist between gallbladder smooth muscle from newborn and adult guinea pigs.…”

Maturational Changes in Airway Smooth Muscle Structure-Function Relationships

“…Other possible causes for the increase in resting tone may include an increase in contractile protein content within each cell (16,17), an increase in the number of crossbridges present, or a difference in geometric conformation of the muscle fibers with age (1 8).…”

“…Seidel et al (16)(17)(18) have shown that the contractile protein/total protein content of vascular smooth muscle increases with age. How myosin content of airway smooth muscle changes with age is less clear.…”