Anti-hypertensive lipid tissue from culture of renomedullary interstitial cells of the rat

1. Allogenic transplants of cultured renomedullary interstitial cells exert a powerful anti-hypertensive action. The blood pressure of hypertensive animals usually drops slowly over 8-12 h whereas the pulse is unchanged or reduced. 2. Lipids derived from the cultured cells exert a similar anti-hypertensive action. 3. The anti-hypertensive action of transplanted cultured cells almost certainly results from the secretion of a substance(s) that acts in the manner of a hormone. The tissue culture lipid is a prime candidate hormone. 4. The relationship of the kidney to the hypertensive state is considered to entail pro- and anti-hypertensive actions. The pro-hypertensive actions include (a) activation of the renal pressor system (mainly renin-angiotensin), (b) failure to prevent sodium and fluid overloading because of either an injured or absent kidney or the excessive action of mineralocorticoids (mainly aldosterone). The antihypertensive actions of the kidney include (a) the relief of sodium and fluid overloading through diuresis-natriuresis and (b) the action of the reno-medullary interstitial cell hormone (the antihypertensive renomedullary hormone).

Functional-morphological correlates of renomedullary interstitial cells

1. Indomethacin treatment of renomedullary interstitial cells (RIC) causes a marked increase in number and size of their lipid droplets. The anti-hypertensive function is retained. 2. After multiple passages in tissue culture, RIC lose their ability to produce an anti-hypertensive effect in hypertensive animals. Along with this functional loss, lipid droplets and a prominent cisternal system become attenuated or disappear. 3. We conclude that preservation of the lipid granule-cisternal organelle relationship is important in preservation of the anti-hypertensive endocrine function of RIC.

Indomethacin and blood pressure control

Blood pressure of indomethacin-treated and control rabbits was measured directly every hour in an automated device for 7 to 10 days. Indomethacin treatment was without effect, and the mean aortic pressure of all rabbits varied generally between 65 and 80 mm. Hg. Since the indomethacin treatment was adequate to block the prostaglandin synthetase system, it is concluded that either circulating prostaglandin is not involved in blood pressure control or other regulatory mechanisms can readily compensate for absence of prostaglandin.

Centre and surround influences on the proximal negative response of the pigeon retina

1. Extracellular field potentials were recorded with micro-electrodes in the inner plexiform layer of the pigeon retina. Stimulus patterns were projected on a tangent screen.2. Maximal responses to a 1 degrees spot were produced from a receptive area 2-3 degrees in extent. Annuli centred over this area produced a different response wave form.3. The responses to centred spots and annuli presented synchronously do not superpose: they interact in a way suggesting transient mutual antagonism. The response to spot onset and offset can be suppressed either by annulus onset or by annulus offset.4. A steady annulus has little effect on the response to spot stimuli, but a steady centred spot enhances the response to annular stimulation.5. The results suggest that the PNR results from convergence of on-centre and off-centre pathways, which are embedded in a widespread suppressive surround.

Renomedullary antihypertensive function in accelerated (malignant) hypertension. Observations on renomedullary interstitial cells

The antihypertensive function of the renal medulla was tested on accelerated (malignant) hypertension of the rabbit. A procedure for the development of accelerated hypertension of the rabbit of lethal proportions within 3 wk was established. This procedure consisted of the application of a rigid clip with a fixed and unyielding gap to the left renal artery and removal of the right kidney. Three additional manipulations, other than simple nephrectomy, were performed on the right kidney after application of the rigid clip to the left renal artery. These were: (a) a sham operation, (b) removal of the kidney and separation of the renal cortex and its autotransplantation in a fragmented state, and (c) removal of the kidney and separation of the renal medulla and its autotransplantation in a fragmented state. After the sham-operated kidney and autotransplanted renal medulla, the standardized accelerated hypertension did not develop, whereas after autotransplanted renal cortex it did. After a period of protection against accelerated hypertension, removal of either the sham-operated kidney or the renomedullary transplants was followed by a prompt rise in arterial pressure and death of the animal. Thus, the antihypertensive action of renomedullary tissue was similar to that of the whole kidney. The main cell type noted in the protective renomedullary transplants had the microscopic characteristics of the lipid-containing interstitial cells. These cells occurred in clusters, often were near capillaries, and appeared hyperplastic. It is suggested that the renomedullary interstitial cell is the most eligible cell for exertion of the renomedullary antihypertensive action. Since vasoactive lipids are extractable from the renal medulla and its interstitial cells, the hypothesis that interstitial cells secrete antihypertensive substance(s) is attractive.

Variations in Thermal Sensitivity

In the past, confusion has resulted from the use of relative expressions indicative of the direction of temperature change, rather than positive identification of warm and cool sensations. Data are presented which show that at more extreme skin temperatures sudden changes in temperature may result in two readily discernible sensations. The occurrence of each sensation depends upon the magnitude of the change.