Pflügers Archiv

Das Ovarium des Meerschweinchens wird durch Temperaturen unter Null so weit geschädigt, daß es als Transplantat nicht Wurzel fassen und nicht zur endokrinen Wirksamkeit gelangen kann; es verfällt nach der Transplantation stets der Degeneration. Dagegen können Ovarien, die 1–16 Tage auf Eis, d. h. bei+1 bis +3° aufbewahrt werden, als Transplantat Wurzel fassen und endokrin wirksam werden. Wie das frisch transplantierte Organ, so bedingt auch das bis 16 Tage außerhalb des Körpers konservierte Ovarium nach der Transplantation ins männliche Meerschweinchen die charakteristische Hyperfeminierung, die in der Umwandlung der Brustwarze und der Brustdrüse im Sinne von Schwangerschaft und Lactation zum Ausdruck kommt. Das nach Konservierung transplantierte Ovarium kann somit im Wirtstier in eine anhaltende Hormonproduktion eintreten. Das nach Konservierung transplantierte Ovarium kann bis über 5 Monate im Wirtstier endokrin wirksam bleiben. Es wurden insgesamt 6 positive Fälle mit 1–3 Tage konservierten Ovarien und 5 positive Fälle mit 7–16 Tage konservierten Ovarien beobachtet. Das Ovarium erfährt jedoch infolge der Konservierung auf Eis eine Schädigung. Diese äußert sich in dreierlei Weise: die Zahl der positiven Fälle ist geringer als bei frisch transplantierten Ovarien; die Latenzzeit ist zuweilen verlängert; das transplantierte und zur endokrinen Wirkung gelangte Ovarium scheint kürzere Zeit zu überleben, als das frisch transplantierte Organ. Es wird die Möglichkeit erörtert, daß die drei verschiedenen Arten der Schädigung in einheitlicher Weise daraus resultieren, daß infolge der Konservierung die weniger widerstandsfähigen Primärfollikel ausgeschaltet werden und auf diese Weise die Zahl der nach Transplantation entwicklungsfähigen Primärfollikel reduziert wird. Es werden zum Schluß einige pathologisch-physiologische Zusammenhänge erörtert.

The purpose of the reported experiments was to examine whether the vagally mediated baroreflex system (V-system) increases its feedback gain with time after sectioning of the carotid sinus nerves (CSN). In 10 dogs anesthetized with Nembutal, we determined the overall open-loop gain (G) of the rapidly acting arterial pressure control system. G was assessed as (ΔAPI/ΔAPS)-1, where ΔAPI and ΔAPS represent the immediate and steady-state decreases in arterial pressure at the aortic arch following a fast step-wise reduction in blood volume. ΔAPI, ΔAPS and GINTACT in the intact condition (30th min before sectioning of the CSN) were −1.8±0.1 kPa, −0.20±0.01 kPa and 8.4±0.3 (mean±SE), respectively. The mean values of ΔAPI, ΔAPS and G after sectioning of the CSN (GV), first averaged within individual dogs and then averaged for ten dogs, were −2.53±0.07 kPa, −1.1±0.05 kPa, and 1.5±0.1, respectively. GV did not change with time over about 4 h after sectioning of the CSN. It is concluded that the V-system cannot augment its ability to restore arterial pressure in compensation for the lost function of the carotid sinus baroreflex system over 4 h after sectioning of the CSN in the anesthetized dog.

Am isolierten, von einem Spendertier durchströmten Hinterleibpräparat des Hundes wurde die fraktionelle ExtraktionE von 4-Aminoantipyrin mit der Indicatordiffusionsmethode bestimmt. Nach einer vonKety angegebenen Formel wurde der capilläre TransportkoeffizientPS errechnet. An dem verwendeten Präparat warPS repräsentativ für die effektive Capillaroberfläche. Vasoconstriction führte bei konstantem Durchfluß zu einer Abnahme vonE undPS. Durchflußzunahme führte bei Blutdruckwerten um 100 mm Hg zu einer geringgradigen Zunahme vonE und bei Blutdruckwerten um 200 mm Hg zu einer Abnahme vonE. Die Zunahme vonPS, die durch Zunahme des Durchflusses bedingt war, war bei Blutdruckwerten um 100 mm Hg größer als bei Blutdruckwerten um 200 mm Hg.PS undE nahmen bei Zunahme des peripheren Widerstandes ab. Die durch Vasoconstriction, Abnahme des Durchflusses oder Zunahme des peripheren Widerstandes bedingte Abnahme von PS war um so geringer, je kleiner der Ausgangswert fürPS war.

The extracellular matrix of adult neural tissue contains chondroitin sulphated proteogylcans that form a dense peri-neuronal net surrounding the cell body and proximal dendrites of many neuronal classes. Development of the peri-neuronal net beyond approximately postnatal day 17 obscures visualization and often access by patch electrodes to neuronal membranes with the result that patch clamp recordings are most readily obtained from early postnatal animals. We describe a technique in which the surface tension of a sucrose-based medium promotes partial dissociation of thin tissue slices from adult tissue. Surface tension spreads the tissue and loosens the peri-neuronal net from neuronal membranes within minutes and in the absence of proteolytic enzymes. Furthermore, the extent of dissociation can be controlled so as to maintain the overall slice structure and allow identification of specific cell classes. Excellent structural preservation of neurons and dendrites can be obtained and full access by patch electrodes made possible for current- or voltage-clamp recordings in tissue well beyond the development of peri-neuronal nets. We demonstrate the feasibility of using this approach through patch recordings from neurons in the brainstem and cerebellum of adult gymnotiform fish and in deep cerebellar nuclei of rats as old as 6 months.

The temporal relationship between intraocular pressure and extraocular muscle activation was studied in cats in response to the administration of the depolarizing muscle relaxant, succinylcholine (i.e. bolus doses of 0.1 and 1.0 mg/kg). Simultaneous changes in intraocular pressure, extraocular muscle force, extraocular electromyograms (EMGs), limb muscle EMGs and hindlimb muscle afferent activity were recorded. Increases in intraocular pressure were associated with extraocular muscle activation and had two components: (1) an initial abrupt increase (lasting seconds) which correlated with fasciculations within the extraocular and hindlimb muscles; and (2) a latter more sustained component (minutes) presumably due to tonic muscle activation which correlated with increases in hindlimb muscle afferent activity (e.g. due to sustained activation of bag 1 intrafusal fibers by succinylcholine). In a separate group of animals, in which the extraocular muscles were detached from the right eye bilateral intraocular pressures were measured: depolarization by succinylcholine caused a significant increase in intraocular pressure only for the eye with intact muscles. Thus, increases in intraocular pressure following the administration of succinylcholine are directly related to the changes in extraocular muscle tension which is dependent on both tonic and phasic muscle fiber responses.

Distributions of sodium and chlorine related to both dry mass and wet tissue volume, and the dry mass distribution were determined in antidiuretic rat kidneys. Using the electron microbe, the measurements were made on freezedried single sections taken from 15–20 different regions throughout the kidney including the extreme tip of the papilla. The sections were taken from kidneys which had been clamped and then rapidly frozen to minimize a redistribution of elements and fluids. A characteristic distribution of dry mass was found, showing a step decrease at the transition of outer and inner zone border and an increase towards the tip of papilla. The changes in dry mass have been interpreted as reflecting differences in water content in various regions. The elemental distributions related to dry mass are much different from those related to tissue volume, the latter being considered to be physiologically more important as they approximate the interstitial concentrations. The distributions of sodium and chlorine by volume rise from constant cortex values up to the outer zone-inner zone border, where the profiles show a discontinuity after which they rise exponentially to the tip of the papilla.

Electrogenic K+ secretion across the distal colon of young rats was investigated by measuring the sensitivity of the short-circuit current to Ba2+ added to the mucosal side of the tissue. Ba2+-sensitive short-circuit current (I sc Ba ) was high during the suckling and weaning periods but very low in adult animals. Increasing the mucosal K+ concentration was accompanied by the inhibition of the serosa-to-mucosaI sc Ba and the induction of the mucosa-to-serosaI sc Ba . TheI sc Ba was decreased by serosal omission of either Na+ or Cl− as well as by serosal addition of furosemide or ouabain. Mucosal omission of Na+ did not changeI sc Ba . By increasing the plasma level of aldosterone (low-sodium diet)I sc Ba rose by 95% whereas treatment decreasing this level (high-sodium diet) reducedI sc Ba by 76%. Bilateral adrenalectomy loweredI sc Ba by 59% and treatment of adrenalectomized rats with deoxycorticosterone acetate prevented the reduction ofI sc Ba . Tetraethylammonium and quinidine had similar effects onI sc as Ba2+. These data are consistent with the presence of a high level of K+ secretion in the distal colon of neonatal rats. This secretory pathway is electrogenic and independent of Na+ absorption. It appears to be mediated by the Na−K-ATPase as well as a furosemide-sensitive Na−Cl or Na−Cl−K cotransport on the basolateral side and by Ba2+-sensitive K+ conductive pathways on the mucosal side. The results suggest that this K+ secretion can be regulated by mineralocorticoids. The mineralocorticoids are necessary for “stimulated” K+ secretion but they are not essential for maintaining “basal” K+ secretion.