- Chronic sildenafil treatment inhibits monocrotaline-induced pulmonary hypertension in rats. Schermuly, R.T., Kreisselmeier, K.P., Ghofrani, H.A., Yilmaz, H., Butrous, G., Ermert, L., Ermert, M., Weissmann, N., Rose, F., Guenther, A., Walmrath, D., Seeger, W., Grimminger, F. Am. J. Respir. Crit. Care Med. (2004)