Transmission of hypertension in rats by cross circulation.

Abstract

Cross circulation was performed in 54 couples of spontaneously hypertensive and normotensive rats. Blood was pumped through two anastomoses between the carotid arteries and external jugular veins in both directions with equal flow rate. In normotensive rats cross-circulated with untreated spontaneously hypertensive rats mean arterial pressure increased by 20.9±12.2 mm Hg (p<0.01). Administration of digoxin antibody in a dose binding 0.25 mg digoxin to the spontaneously hypertensive rats before cross circulation prevented the transmission of hypertension to the normotensive rat, whereas chemical sympathectomy with 6-hydroxydopamine and intravenous injection of inactive Fab fragments had no inhibitory effect. It is concluded that, in this strain of spontaneously hypertensive rats, a circulating hypertensive factor exists. The factor binds to digoxin antibody and is not produced in sympathetic nervous tissue. (Hypertension 1989;14:61-65) T here are several indications for the role of a circulating vasopressor agent in primary hypertension. First, hypertensive plasma enhances the vasoconstrictor effect of noradrenaline and angiotensin II. -2 Second, parabiosis experiments with spontaneously hypertensive rats demonstrated the transmission of hypertension.3 -5 Third, injection of hypertensive plasma or other blood components increased blood pressure in normotensive rats.6 -8 Likewise, a transmission of hypertension from spontaneously hypertensive to normotensive rats has been demonstrated by cross circulation. 9Early experiments with parabiosis 10 ' 11 and recent cross circulation studies pointed to an important role of kidneys and adrenal glands for the production of the hypertensive factor. Injection of plasma from nephrectomized hypertensive rats failed to increase blood pressure in normotensive rats. 6 The transmission of hypertension by cross circulation can be prevented by nephrectomy and adrenalectomy in the spontaneously hypertensive rat. 9Although the production of the hypertensive factor in the spontaneously hypertensive rat was localized by several studies in the kidneys or adrenal glands, the structure of the hypertensive factor is yet unknown. Therefore, in the present study, cross circulation was used as a bioassay of the circulating hypertensive factor.From the Medical University, Poliklinik, Albert-Schweitzer, MOnster, FRG.Address for correspondence: Dr. Walter Zidek, AlbertSchweitzer-Str. 33, D-4400, Mflnster, FRG.Received March 10, 1987; accepted January 19, 1989. As to the nature of the yet unidentified agent, several lines of evidence point to a circulating sodium-potassium adenosine triphosphatase (Na,K-ATPase) inhibitor. First, in essential hypertensive individuals the ability of plasma to inhibit Na,K-ATPase has been repeatedly demonstrated. Recently, neuropeptide Y has been described as a vasopressor and natriuretic agent 23 -24 and may thus fulfill the criteria for the hypothetical natriuretic hormone. Neuropeptide Y has been shown to be produced in sympathetic nerve cells, 25 and its sy...

Effects of Protein Kinase C Activation on Intracellular Ca2+ Distribution in Vascular Smooth Muscle Cells of Spontaneously Hypertensive Rats

“…All experiments were carried out using rat thoracic aortas isolated from 6-month-old male spontaneously hypertensive rats (SHR) of the Münster strain (weight 300-400 g. systolic blood pressure 195 ± 4 mm Hg, mean ± SEM) as previously described [12] and agematched male normotensive Wistar-Kyoto rats (WKY, systolic blood pressure 116+3 mm Hg). Vascular smooth muscle cells (VSMC) were cultured according to previously described methods [13,14], Briefly, cells were incubated in Dulbecco's modified Eagle medium (Gibco.…”

A Novel Platelet-Derived Renal Vasoconstrictor Agent in Normotensives and Essential Hypertensives

“…In spontaneously hypertensive rats, parabiosis experiments [2,3] and, more recently, crosscirculation studies [4] also suggested a circulating pressor sive factor in spontaneously hypertensive rats. Similarly, in plasma of essential hypertensives, a vasopressor frac tion could be identified by intravenous injection in rats [10].…”

Reduced sodium-proton exchange activity in lymphocytes from transgenic rats.

“…SHR from the Munster strain as previously described 15 and the normotensive WistarKyoto (WKY) control strain were obtained from Medizinische Poliklinik, Munster, Germany. The rats were fed a standard pellet diet and allowed tap water ad libitum.…”