Endothelin-1 (ET-1) is an endothelium-derived potent vasoconstrictor peptide that potentiates contractions to norepinephrine in human vessels. We previously reported that the circulating plasma concentration of ET-1 is significantly increased after exercise (S. Maeda, T. Miyauchi, K. Goto, and M. Matsuda. J. Appl. Physiol. 77: 1399-1402, 1994). To study the roles of ET-1 during and after exercise, we investigated whether endurance exercise affects the production of ET-1 in the circulation of working muscles and nonworking muscles. Male athletes performed one-leg cycle ergometer exercise of 30-min duration at intensity of 110% of their individual ventilatory threshold. Plasma concentrations of ET-1 in both sides of femoral veins (veins in the working leg and nonworking leg) and in the femoral artery (artery in the nonworking leg) were measured before and after exercise. The plasma ET-1 concentration in the femoral vein in the nonworking leg was significantly increased after exercise, whereas that in femoral vein in the working leg was not changed. The arteriovenous difference in ET-1 concentration was significantly increased after exercise in the circulation of the nonworking leg but not of the working leg, which suggests that the production of ET-1 was increased in the circulation of the nonworking leg by exercise. The present study also demonstrated that the plasma norepinephrine concentrations were elevated by exercise in the femoral veins of both the working and nonworking legs, suggesting that the sympathetic nerve activity was augmented in both legs during exercise. Therefore, the present study demonstrates the possibility that the increase in production of ET-1 in nonworking muscles may cause vasoconstriction and hence decrease blood flow in nonworking muscles through its direct vasoconstrictive action or through an indirect effect of ET-1 to enhance vasoconstrictions to norepinephrine and that these responses may be helpful in increasing blood flow in working muscles. We propose that endogenous ET-1 contributes to the exercise-induced redistribution of blood flow in muscles.

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The board certification system in Japan is undergoing reform, but it is likely to be watered down without significant improvement.

ulmonary capillary wedge pressure (PCWP) is an important clinical marker of cardiac function, 1-3 but measuring it requires right heart catheterization, which limits longterm monitoring or its use as a screening test. Therefore, a simple, reliable, and noninvasive method of estimating PCWP is required.Previous experimental studies have shown that left atrial pressure (LAP) is the most effective component of the transmitral flow velocity profile (TMF) obtained by pulsed Doppler echocardiography, 4-9 and there have been numerous investigations of the relationship between Doppler variables, including the early diastolic transmitral flow peak velocities (E), the late diastolic transmitral flow peak velocities (A), the ratio E to A (E/A), the deceleration time of E (DT) and the isovolumic relaxation time (IVRT), and PCWP or left ventricular end-diastolic pressure (LVEDP). 12-15 Some clinical studies have pointed out, however, that TMF cannot be used in all types of patients to estimate PCWP, because the relationship between PCWP and Doppler variables varies with the subject. 16,17 Other studies have also suggested that the LAP can be estimated more accurately using combinations of Doppler variables [18][19][20][21][22][23][24][25] ; for example, it has recently been shown that the propagation velocity (PV) of early diastolic left ventricular (LV) inflow based on color Doppler M-mode measurements was found to correlate well with the time constant of isovolumic LV relaxation (tau), and may be used to evaluate LV relaxation. 27,28,30,32 On the basis that Japanese Circulation Journal Vol.65, January 2001 E depends on LAP and LV relaxation, 9-11 the ratio of E and PV (E/PV) has been shown to correlate well with PCWP. [23][24][25] However, we considered that PCWP might correlate well with multilinear regression analysis using E and PV in the interpretation of the determinant component of E. Accordingly, the present study was designed to evaluate whether a multilinear regression model based on E and PV can estimate PCWP more accurately than other Dopplerbased methods in various cardiac disease states. Methods Study ProtocolIn the initial study group, Doppler echocardiography and cardiac catheterization were performed simultaneously, and an equation to estimate PCWP was obtained by multilinear regression analysis using E and PV. The reliability of the obtained equation was then tested prospectively in a second population (test population). In this second study, the patients were classified into 3 groups based on LV function and morphology: (1) LV systolic dysfunction, (2) LV hypertrophy, and (3) no evidence of LV systolic dysfunction or hypertrophy. We determined the correlations between PCWP and Doppler TMF variables, and between the estimated PCWP obtained from the regression equation and the PCWP measured using a Swan-Ganz catheter. All patients gave written informed consent before participation. Initial Study GroupThe initial group comprised 30 patients (21 men, 9 women) whose ages ranged from 35 to 80 years (mean, 57±19...

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