Venous smooth muscle tone and responsiveness in older adults

Abstract

Venous compliance is lower in older adults compared with younger adults. It is possible that alterations in venous smooth muscle tone and responsiveness may contribute to the age-related differences in venous compliance. To determine the effects of sympathetic activation [cold pressor test (cold pressor test); rhythmic ischemic handgrip (rhythmic ischemic handgrip)] and endothelium-independent decreases in smooth muscle tone [sublingual nitroglycerin (nitroglycerin)] on venous compliance in young and older adults, forearm and calf venous compliance was measured in 12 young (22 +/- 1 yr) and 12 old (65 +/- 1 yr) supine subjects using venous occlusion plethysmography. Venous compliance was assessed at baseline, during the cold pressor test and rhythmic ischemic handgrip tests, and after nitroglycerin administration. All pressure-volume relationships were modeled with a quadratic regression equation, and beta1 and beta2 were used as indexes of venous compliance. A repeated-measures ANOVA was used to determine the effect of the age and trial on venous compliance. Calf regression parameters beta1 (0.0639 +/- 0.0126 vs. 0.0503 +/- 0.0059, young vs. older; P < 0.05) and beta2 (-0.00054 +/- 0.00011 vs. -0.00041 +/- 0.00005, young vs. older; P < 0.05) were significantly less in older adults at baseline. Similarly, forearm regression parameters, beta1 and beta2 were lower in older adults at baseline. Venous compliance was not effected by the cold pressor test test, rhythmic ischemic handgrip, or sublingual nitroglycerin in either group. Data suggest that forearm and calf venous compliance is lower in older adults compared with young. However, this difference probably cannot be explained by alterations in smooth muscle tone or responsiveness.

Peripheral venous distension elicits a blood pressure raising reflex in young and middle-aged adults

“…Although infusion volumes were individually determined by estimated forearm volume, we did not quantify the actual distension of the veins. This could be important since venous compliance is diminished with increased age (20,34). However, in spite of potential alterations in the stimulus due to age-related differences in venous compliance, the venous distension reflex was not attenuated in the middle-aged adults.…”

Non-invasive Serum Cholesterol Detection Using Near-infrared Light Transmission

“…However, because arteriosclerosis commonly occurs at sites where blood vessels curve and branch, there is less possibility that increased blood cholesterol is directly involved in this pathology, although it is possible that it has an effect on vascular stiffness. The main cause of vascular stiffness is aging [25,26]. The vascular wall consists of elastin and collagen [27].…”

Limb venous compliance responses to lower body negative pressure in humans with high blood pressure

“…This rate of cuff deflation was chosen based on the evidence that intravenous pressure tracks collecting cuff pressure, when cuff pressure drops at a rate of B1 mm Hg sec À1 . 19,20 During the deflation period, changes in limb volume measured by the strain gauge and the drop in collection pressure were recorded and used to create the volume-pressure curves. Cuff pressure was used as a surrogate of intravenous pressure.…”

“…Cuff pressure was used as a surrogate of intravenous pressure. 19 Previous studies have determined the relationship between collecting cuff pressure and intravenous pressure in young (r ¼ 0.998) and older NT adults (r ¼ 0.999), 20 as well as in hypertensive subjects (r ¼ 0.998). 11 In our laboratory, the coefficient of variation of this method is o10% (measurements obtained on two separate days in a sample of 14 subjects).…”

“…Previous studies have shown that this time period is sufficient to allow for reproducible measurements of limb venous compliance in humans. 20 LBNP testing. Subjects were in the supine position enclosed in a one-legged chamber, up to the level of the umbilicus.…”