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Biomedical subjects

D Ben-Ishay

Publications and source records attributed to D Ben-Ishay.

At least 73 records · Page 4Linked to original sources
PubMed1982

Catecholamines and vasopressin in hindbrain nuclei of hypertension prone and resistant rats.

Norepinephrine and epinephrine concentrations in the caudal and rostral part of the nucleus tractus solitarii (NTS) and in locus coeruleus (LC) of Sabra hypertension prone (SBH) rats are 2-4-fold higher than in the parent Sabra (SB) strain; SB rats have higher concentrations than the Sabra hypertension resistant (SBN) rats. Dopamine concentrations were higher in SBH as compared to SB and SBN rats only in the caudal NTS. Vasopressin concentrations in the NTS of SBH were 3-fold higher than the levels found in SB or SBN rats. These data suggest that catecholamines and vasopressin in specific brainstem nuclei are involved in either the pathogenesis or central response to hypertension in SBH rats.

Animals↗
PubMed1982

Erythrocytic sodium ion transport systems in primary and secondary hypertension of the rat.

Sodium and potassium ion transport systems were studied in erythrocytes from spontaneously hypertensive Okamoto rats (SHR), hypertension-prone Sabra rats (SbH), and one-kidney one-clip Goldblatt hypertensive rats, and compared with Wistar-Kyoto normotensive rats (WKY), hypertension-resistant Sabra rats (SbN), and sham-operated Wistar rats. We observed the following: (1) An increased net potassium influx and a reduced net sodium extrusion occurred in SHR. The increased potassium influx was inhibited by ouabain, indicating an increased sodium ion pump activity. Bumetanide-sensitive sodium extrusion was lower in SHR than it was in WKY, indicating abnormally low outward sodium-potassium cotransport fluxes. (2) Passive sodium ion permeability was increased in SbH compared with SbN. Cotransport was normal in SbH rats. (3) Sodium-potassium cotransport and passive permeability were normal in renovascular hypertension. (4) After a chronic or acute sodium load, the sodium content increased in erythrocytes from SHR and SbH but not in those of normotensive or renal hypertensive rats. It appears therefore that erythrocyte membrane abnormalities leading to an increased intracellular sodium concentration are only present in genetic hypertension. The reduction of outward sodium-potassium cotransport observed in SHR is identical to that previously reported in human essential hypertension, suggesting that it may be considered as a genetic marker.

Animals↗
PubMed1981

Catecholamines and vasopressin in forebrain nuclei of hypertension prone and resistant rats.

Catecholamine and vasopressin content were studied in discrete brain nuclei of the Sabra strain of hypertension prone (SBH) and resistant (SBN) rats. Higher concentrations of dopamine, norepinephrine and epinephrine were observed in the median eminence of SBN compared to SBH or controls (SB) rats. Dopamine and epinephrine levels were higher in the lateral septal nucleus of SBH rats as compared to SBN or SB. Vasopressin content in discrete regions along the hypothalamo-pituitary axis was elevated in both SBH and SBN as compared to SB, but were especially elevated in the SBH group. The catecholamine and vasopressin changes found in SBH are different than those described in other genetically hypertensive rats indicating a difference in either the pathogenesis or central response to hypertension of this strain.

Animals↗
PubMed1981

Cyclic AMP generation in medulla oblongata and hypothalamus of hypertension-prone and -resistant rats.

Accumulation of cAMP induced by noradrenaline (NA) was higher in the medulla oblongata (MO) of hypertension-prone (H) than in resistant (N) rats, 113 +/- 3 vs. 72 +/- 4 (p less than 0.01). In the hypothalamus (HYP) it was higher in N than in H rats, 148 +/- 8 vs. 92 +/- 6 (p less than 0.01). In both anterior and posterior HYP, the accumulation of cAMP was significantly higher in N than in H rats. cAMP accumulation, in the presence of increasing concentrations of phosphodiesterase inhibitor, showed significant strain differences in both MO and HYP. The observed strain differences in cAMP may be pertinent to the disparate susceptibility to hypertension of H and N rats.

Animals↗
PubMed1981

Distinguishing traits in the Sabra hypertension-prone (SBH) and hypertension-resistant (SBN) rats.

Distinct differences in central and peripheral noradrenaline (NA) were observed in the hypertension prone (SBH) and resistant (SBN) strain, derived from the Hebrew University SABRA rats. In the medulla oblongata NA concentration was 90% higher and tyrosine hydroxylase activity 88% lower in SBN when compared to SBH, suggesting marked strain differences in NA turnover. In this area, NA-induced cAMP generation was higher in SBH than in SBN, while the hypothalamus, the reverse situation was present. The relevance of hypertension of the reciprocal cAMP changes is still uncertain. The concentration of NA in heart tissue was significantly higher in SBN than in SBH. Doca-salt treatment caused hypertension and depletion of atrial NA in SBH, but had no effect on either blood pressure or atrial NA in SBN rats. The results suggest that resistance to hypertension in SBN rats is associated with decreased NA turnover in medulla oblongata and reduced activity of cardiac neuronal sympathetic endings.

Animals↗
PubMed1980

[Increased erythrocyte Na+ in genetic hypertension in the rat].

A rise in erythrocyte Na+ content secondary to a sodium rich diet has been observed in genetically hypertensive Rats and in Rats with a predisposition to develop hypertension under the influence of Na+ loading. In contrast, such a rise is absent in Rats with a genetic resistance to the development of hypertension. Hence, the determination of erythrocyte Na+ after exposure to a sodium load may permit the characterization of primary hypertension.

Animals↗
PubMed1980

Cyclic AMP generation in hypothalamus of hypertension-prone and -resistant rats.

1. This noradrenaline-induced accumulation of cyclic AMP is decreased in both the anterior and the posterior hypothalamus of hypertension-prone as compared with resistant rats, but is similar in the cortex. 2. The noradrenaline-induced accumulation of cyclic AMP is decreased in the posterior hypothalamus as compared with the anterior hypothalamus of both strains. 3. The decreased sensitivity to phosphodiesterase inhibitor in the hypothalamus of hypertension-prone as compared with resistant rats suggests that strain differences in phosphodiesterase activity may exist. 4. Since differences in cyclic AMP were found in the hypothalamus and the medulla oblongata, regions involved in blood pressure control, but not in the cortex, they may be relevant to the diverse susceptibility to hypertension of hypertension-prone and resistant rats.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1980

Abnormal net Na+ and K+ fluxes in erythrocytes of three varieties of genetically hypertensive rats.

Net Na+ and K+ fluxes were measured in Na+-loaded and K+-depleted erythrocytes of three varieties of genetically hypertensive rats. In Okamoto spontaneously hypertensive rats (4 and 10-12 weeks of age), Na+ extrusion was reduced as compared to normotensive controls (Wistar/Kyoto). Na+ extrusion was also reduced in the hypertension-prone substrain of the Hebrew University Sabra rats as compared to the Na+-resistant substrain. K+ fluxes were similar in both groups. In both Okamoto spontaneously hypertensive rats and the hypertension-prone substrain, hypertension was severe and developed rapidly. In the Lyon spontaneously hypertensive rats, in which the blood pressure elevation is less severe than in other genetically hypertensive rats, erythrocyte net Na+ extrusion was the same as in normotensive controls, but net K+ gain was slightly increased. These erythrocyte abnormalities, observed in three varieties of genetically transmitted hypertension of the rat, are in several aspects similar to those previously described in accelerated and benign human essential hypertension. Erythrocyte Na+ and K+ net flux alterations may thus represent biochemical markers of primary hypertension.

Animals↗
PubMed1980

The Sabra hypertension prone (H) and hypertension resistant (N) rat strain.

By selective inbreeding of the Hebrew University Sabra rat, we have obtained a hypertension prone (H) and a hypertension resistant (N) substrain. The criteria for selection was the blood pressure response to DOCA-salt. The outstanding element of our model is the N rat with its remarkable resistance to hypertension. When compared to H, the N rat presents the following characteristics: 1. The blood pressure of experimentally naive N rats is significantly lower at comparable ages, in both sexes. 2. N rats are resistant to both DOCA-salt and renal clip hypertension. 3. In the medulla oblongata (MO) of N rats, the noradrenaline (NA) content is significantly higher and the activity of tyrosine hydroxylase is significantly lower. 4. In the MO of N rats, the sensitivity of the NA dependent cAMP generating system is significantly decreased. 5. In the atrium of N rats, the NA content is significantly higher, and is unaffected by DOCA-salt treatment. The results suggest that genetic differences in catecholamine metabolism may account for the disparate susceptibility to hypertension of the two strains.

Animals↗