When the rat aorta is excised and placed in a bath of Krebs' solution it loses over two-thirds of its potassium and gains roughly an equivalent amount of sodium within the first 15 seconds. If the aorta is placed in rat plasma instead of Krebs' solution, a similar change occurs. These rapid changes in aorta electrolyte composition do not occur when the whole rat is perfused with Krebs' solution. It is concluded that in the handling involved in the removal of the aorta its cell membrane barriers are altered in such a way that they no longer maintain the normal transmembrane gradients of these cations. After 2 minutes in the bath the potassium in the aorta gradually increases and its sodium decreases suggesting that the cell membrane has regained its characteristics as a barrier and is capable of maintaining sodium and potassium gradients established by an active transport system.
TI-~ ~r~vENOUS ADMINISTtLZxTION Of local anaesthet, tc drugs ,n chmcal medmme was mataated by Bmr m 1908 Holmes, 1 an Februat3t 1963, reported ,,tlnrty eases for wll~eh he employed a mo&:fieatmn of Bier s ve~ous anaesthesm The teehtuque has been readily adopted by the Anaesthetm team m the new Teadnng Hospatal an Lagos, where many patmnts appear ]l[or emergency treatment of lesmns of the extrem~tles The 514 patmnts m thJis series wexe anaesthetized dunng the eaght-month permd from April to December, 198a They were unpremedmated and unprepared an that food had poss~b]qy been eaten w~thm a short t-,me of anaval METHODS A sphygmomanometer cuff was apphed to the affdcted extremity of the recumbent pataent and the blood pressure was measure, prior to drainage of the extremity and again one minute after final release of the tourmquet For hand refections the anaesthetist had the choice of applying the cuff above or below the elbow A 20-e e syringe loaded with hgnoeame was attached to a needIe (SWG 22), whmh was introduced into a statable veto distal to the cuff After elevating the extremity for one minute to allow venous dramagej the cuff was inflated above the systohe pressure, the extrematy was returned to the honzontal positron, and the so]utlon of hgnoeame was administered m a single mjeetmn The surgeon then prepared the extremity and performed the necessary operatmn, the dressing was apphed, and the sphygmomanometer cuff was deflated Holmes and Baer preferred the Esmareh bandage for the exsangumatmn ot the extremity, but m the few eases m whmh at was used here, at afforded no pmtmular advantage over the method of grawtatmnal drainageThe eoneentratmn of hgnoeame used vaned between 0 5 and 2 0 per cent, wh~Ie the rejected volume ranged from 10 to 40 c e for the first 150 patmnts Then ~t was demded that a I per cent hgnoeame solutmn was the most satasfaetory and that 20 e e would be adequate for an adult The majority of the patmnts were 20 to 60 years of age and reqmred this chosen hgnoeame dosage of 20(}1 mg Children up to 15 years of age and patmnts over (}0)rears were gwen smaller doses as determined by each mvestagatm for the mdwadual patmntThe surgmal procedure was begun two to five minutes after the mjeetmn of the hgnoeame, and was completed usually m less than five minutes, so that the
Tissue electrolytes in the early phase of hypertension initiated by DCA have been compared with those in later persistent hypertension. In smooth muscle (aorta and stomach muscle) significant potassium depletion occurs during early hypertension in comparison with tissues from treated normotensive animals. A tendency for increased sodium concentration also developed. However, no significant changes from normotensive controls could be demonstrated in aorta during post-DCA, renal or spontaneous hypertension of long duration. These results suggest that there are differences in the disturbances in vascular smooth muscle electrolytes accompanying early and late hypertension. Differences in age or composition of the control groups and in the degree of hypertension produced may explain differences between these results and those of previous workers. None of the other tissues analyzed (left ventricle and psoas muscle) showed changes in electrolyte distribution characteristic of chronic hypertension.
Intravenous norepinephrine (1.0 µg/kg body weight) produced a strikingly uniform pressor effect in rats. The average blood pressure rise was 54 mm Hg, the peak rise occurred in less than 20 seconds, and the blood pressure returned to baseline in about 2 minutes. The aorta was rapidly depleted of potassium (15–18%) by the norepinephrine injection, depletion occurring within 20 seconds (time required for exsanguination) after the peak of the pressor effect and persisting throughout the period of the pressor response. Aorta sodium concentration did not increase concomitantly either in time or in quantity. No other tissue studied (stomach muscle, left ventricle, psoas muscle) showed a parallel alteration in electrolytes. Therefore, injections of norepinephrine appear to selectively affect permeability of vascular smooth muscle to potassium.
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