1. Hess, S. M., Connamacher, R. H., Ozaki, M., and Udenfriend, S., J. Pharmacol. Exp. Therap., 134, 129 (1961).
2. Porter, C. C., Totaro, J. A., and Leiby, C. M., J. Pharmacol. Exp. Therap., 134, 139 (1961).
3. Gillespie, L., Oates, J. A., Crout, J. R., and Sjoerdsma, A., Circulation, 25, 281 (1962).
4. Day, M. D., and Rand, M. J., Brit. J. Pharmacol., 22, 72 (1964).
5. Brown, G. L., and Gillespie, J. S., J. Physiol., 138, 81 (1957).