Rôle of the Sympathetic Nervous System in Experimental Neurogenic Hypertension

Recent clinical studies 1 have renewed interest in central or psychosomatic factors in essential hypertension. The sustained neurogenic hypertension in dogs described by Heymans and Bouckaert 2 seems from this point of view to afford a better experimental approach to the problem of hypertension and sympathectomy than the renal hypertension described by Goldblatt, 3 and shown to be uninfluenced by total sympathectomy. 4-7 The recent demonstration, Grimson, Bouckaert and Heymans, 8 that a sustained neurogenic hypertension of renal origin may be produced by a central reflex mechanism tends to correlate these two methods for producing experimental hypertension. The present study is based upon an effort to determine the blood pressure levels produced by section of the depressor nerves in normal dogs and compare them with the pressure levels produced by the same procedure in dogs sympathectomized with the exception of the nerve supply to the kidneys and adrenals, as well as to study the effects of renal denervation, splanchnic resection, and total para-vertebral sympathectomy on the former group.

Heymans and Bouckaert 9 have shown that section of the depressor nerves produces a persistent hypertension and that total sympathectomy eliminates the hypertension. Goldblatt, Kahn, Bayless. and Simon 10 have recently failed to obtain this type of hypertension and Nowak and Walker 11 have stated that some hypertension follows depressor nerve section in sympathectomized dogs. These contraindications have further stimulated this study.

In 9 dogs both carotid sinuses were excised, the left vago-sympathetic-depressor nerve was cut, and a segment of the right sympathetic depressor trunk was removed. The control blood pressures were respectively 131, 133, 134, 134, 138, 138, 144, 148 and 174.