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Accurate sizing of vessel diameter is important for understanding the physiology of blood vessels as well as the treatment of coronary and peripheral artery disease. The objective of this study was to validate a novel catheter-based system [the LumenRECON (LR) system] for the real-time reconstruction of lumen cross-sectional area (CSA) along the length of a vessel segment. A total of 22 swine (20 Yorkshire and 2 atherosclerotic Ossabaw swine) were used to evaluate the accuracy, reproducibility, and safety of the system compared with intravascular ultrasound (IVUS). The CSA of the right coronary artery, left anterior descending coronary artery, and left circumflex artery were determined by IVUS and the LR system over a 3- to 4-cm segment in 12 Yorkshire and 2 atherosclerotic Ossabaw swine and 2 postmortem atherosclerotic human hearts. In eight chronic animals, the effect of the LR catheter on the vessel wall was evaluated at 1 day and 2 wk (4 animals each) after the intervention. A Bland-Altman plot of the LR and IVUS data showed a mean difference between the two measurements of 0.055 mm in diameter, which was not statistically significant from zero, indicating a lack of bias in the comparison of the LR system with IVUS. The root mean square error of the two measurements was 10.2% of the mean IVUS diameter. The repeatability of the LR system was assessed using duplicate measurements. The mean of the difference between the two measurements was nearly zero, and the repeatability coefficient was within 4.5% of the mean of the two measurements. No injury or intimal hyperplasia was found acutely or chronically after the use of the LR system. This study establishes the accuracy, reproducibility, and safety of a nonimaging 2.7-Fr catheter for lumen sizing of coronary arteries. The system provides a continuous quantitative axial profile of the mean vessel lumen in real time and may have significant utility in vascular research and clinically in the catheterization laboratory. [ABSTRACT FROM AUTHOR]

Spontaneous transient outward K+ currents (STOCs) elicited by Ca2+ sparks and steady-state K+ currents modulate vascular reactivity, but effects of artery size. diabetic dyslipidemia, and exercise on these differentially regulated K+ currents are unclear. We studied the conduit arteries and microvessels of male Yucatan swine assigned to one of three groups for 20 wk: control (C, n = 7), diabetic dyslipidemic (DD. n = 6), or treadmill trained DD animals (DDX, n = 7) Circumflex artery blood flow velocity obtained with intracoronary Doppler and lumen diameters obtained by intravascular ultrasound enabled calculation of absolute coronary blood flow (CBF) Ca2+ sparks were determined in pressurized microvessels, and perforated patch clamp assessed K+ current in smooth muscle cells isolated from conduits and microvessels. Baseline CBF in DD was decreased versus C In pressurized microvessels. Ca2+ spark activity was significantly lower in DD versus C and DDX (P < 0.05 vs. DDX). STOCs were pronounced in microvessel (∼35 STOCs/min) in sharp contrast to conduit cells (-∼2 STOCs/min), STOCs were decreased by 86% in DD versus C and DDX in microvessels: in contrast, there was no difference in STOCs across groups in conduit cells Steady-state K+ current in microvessels was decreased in DD and DDX versus C; in contrast. sleady-state K+ current in conduit cells was decreased in DDX versus DD and C, We conclude that steady-state K+ current and STOCs are differentially regulated in conduit versus microvessels in bealth and diabetic dyslipidemia. Exercise prevented diabetic dyslipidemia-induced decreases in baseline CBF, possibly via STOC-regulated basal microvascular tone. [ABSTRACT FROM AUTHOR]

Physical inactivity is an independent risk factor for coronary heart disease, yet the mechanism(s) of exerciserelated cardioprotection remains unknown. We tested the hypothesis that coronary smooth muscle after exercise training would have decreased mitogen-induced phenotypic modulation and enhanced regulation of nuclear Ca[sup 2+]. Yucatan swine were endurance exercise trained (EX) on a treadmill for 16-20 wk. EX reduced endothelin-1-induced DNA content by 40% compared with sedentary (SED) swine (P < 0.01). EX decreased single cell peak endothelin-1-induced cytosolic Ca[sup 2+] responses compared with SED by 16% and peak nuclear Ca[sup 2+] responses by 33% (P < 0.05), as determined by confocal microscopy. On the basis of these results, we hypothesized that sarco(endo)plasmic reticulum Ca[sup 2+]-ATPase (SERCA) and intracellular Ca[sup 2+] stores in native smooth muscle are spatially localized to dissociate cytosolic Ca[sup 2+] and nuclear Ca[sup 2+]. Subcellular localization of SERCA in living and fixed cells revealed a distribution of SERCA near the sarcolemma and on the nuclear envelope. These results show that EX enhances nuclear Ca[sup 2+] regulation, possibly via SERCA, which may be one mechanism by which coronary smooth muscle cells from EX are less responsive to mitogeninduced phenotypic modulation. [ABSTRACT FROM AUTHOR]