Klaus Golenhofen

Die Beziehungen des Blutdruckrhythmus zu Atmung und peripherer Durchblutung

ZusammenfassungIn der Blutdruckkurve treten besonders Wellen einer Frequenz um 5–7/min hervor (schneller Typ der Wellen 3. Ordnung, THM-Wellen), während sich in der peripheren Durchblutung (Muskel und Haut) vorwiegend Wellen einer Periodendauer um 1 min finden. Diese beiden Rhythmen werden nach ihrer bevorzugten Frequenz als 10 sec-Rhythmus und 1 min-Rhythmus bezeichnet.10 sec-Rhythmus und Atmung sind in Form einer relativen Koordination miteinander gekoppelt, deren Mechanismus diskutiert wird. Die Blutdruckwellen können nicht als Regelschwankungen des Blutdruckes um einen konstanten Sollwert erklärt, sondern dürfen vielmehr als spontan-rhythmische Sollwertverstellungen aufgefaßt werden.Der 1 min-Rhythmus der peripheren Durchblutung ist dadurch gekennzeichnet, daß die Durchblutungsschwankungen in verschiedenen Gefäßbezirken einander kompensieren — vielleicht unter Beteiligung des Herzminutenvolumens —, so daß der zentrale Blutdruck an diesem Rhythmus in der Regel nicht teilnimmt.Die Nomenklatur der Kreislaufrhythmen wird diskutiert, 10 sec- und 1 min-Rhythmus werden in das Gesamtspektrum menschlicher Rhythmen eingeordnet.

Direct effects of motilin on isolated smooth muscle from various regions of the human stomach

The effects of motilin on gastrointestinal muscles show great variations in different organs and different species. For a precise regional differentiation, we recorded the mechanical activity of longitudinal and circular strips from fundus, corpus and antrum and of circular preparations from the inner and outer layer of the pyloric sphincter and from the duodenum (20 human stomachs). Motilin produced excitatory effects on the mechanical activity of the circular muscle strips from all regions of the human stomach including the pylorus. The effects on longitudinal preparations and on duodenal strips were weak. The most striking effect was an increase of phasic activity (amplitude) in circular antrum preparations, which exceeded the acetylcholine- and bombesin-induced activity. In pylorus preparations, a strong stimulation of phasic activity was observed with a transition to tonic activity in the inner layer of the pyloric ring at high motilin concentrations. The motilin-induced activity of the pyloric preparations was greater than the acetylcholine-induced contractions and even exceeded the bombesin-induced responses in the outer pylorus. The responses of the muscle strips of the proximal stomach (fundus and corpus) were weaker and did not exceed the acetylcholine-induced activity. All effects remained unaltered by atropine and tetrodotoxin application. The study confirms that motilin can interact directly with the smooth muscle of human stomach.

Psychische Einflsse auf die Muskeldurchblutung

ZusammenfassungWährend verschiedener psychischer Einflüsse wurde die Muskeldurchblutung mit der Wärmeleitsonde nach Hensel fortlaufend registriert bei gleichzeitiger Messung von Hautdurchblutung und Pulsfrequenz. Als Test dienten die Ankündigung einer i.v. Injektion und die Verabreichung einer als Adrenalingabe bezeichneten Injektion von physiologischer Kochsalzlösung. In einer weiteren Anordnung wurde von der Vp. geistige Leistung in Form von Kopfrechnen gefordert.Die auftretenden Mehrdurchblutungsreaktionen der Muskulatur können auf verschiedene Mechanismen zurückgeführt werden: a) vasomotorische Einflüsse, b) Steigerung des reflektorischen Muskeltonus mit sekundärer Durchblutungserhöhung, c) Adrenalinausschüttungen.Die Frage der Zuordnung von Stärke und Inhalt der Affekte zu diesen Reaktionsformen wird diskutiert.

Fortlaufende Registrierung der Leberdurchblutung mit der Wrmeleitsonde

Mit der Warmeleitsonde nach Hensel wurden Warmeleitzahl- und Durchblutungsmessungen in der Leber durchgefuhrt. Die Warmeleitzahl der undurchbluteten Menschenleber, im Durchschnitt 11,3 · 10−4 cal × cm−1 · s−1 · °C−1, wird durch pathologische Gewebsveranderungen wie Stauungsleber, verschiedene Formen der Atrophie, carcinomatose und cirrhotische Veranderungen nicht mesbar beeinflust. Lediglich bei Leberverfettung erfahrt sie eine merkliche Verminderung.ZusammenfassungMit der Wärmeleitsonde nach Hensel wurden Wärmeleitzahl- und Durchblutungsmessungen in der Leber durchgeführt. Die Wärmeleitzahl der undurchbluteten Menschenleber, im Durchschnitt 11,3 · 10−4 cal × cm−1 · s−1 · °C−1, wird durch pathologische Gewebsveränderungen wie Stauungsleber, verschiedene Formen der Atrophie, carcinomatöse und cirrhotische Veränderungen nicht meßbar beeinflußt. Lediglich bei Leberverfettung erfährt sie eine merkliche Verminderung.Bei isolierter Durchströmung von Hundelebern fand sich eine nicht lineare Abhängigkeit der Wärmeleitzahl vom Stromzeitvolumen. Die mittlere Wärmeleitzahl der undurchbluteten Hundeleber beträgt 11,0 · 10−4, die Wärmeleitzahlerhöhung bei Durchblutung im Mittel 3,9 · 10−4. Die Streuung der Werte bei durchbluteter Leber ist erheblich. Unterschiedliche Blutfülle beeinflußt die Wärmeleitfähigkeit der Leber nicht.Mit einem besonders konstruierten flexiblen Typ der Wärmeleitsonde ist die fortlaufende Registrierung relativer Durchblutungsänderungen auch am wachen Tier und am wachen Menschen möglich.

Differentiated contractile responses of gastric smooth muscle to substance P

Muscle strips were excised from the circular and longitudinal layers of the fundus, corpus and antrum of canine stomach, and from the inner portion of the pyloric ring (inner pylorus). Substance P (SP) induced strong contractions, with the greatest sensitivity in fundus and circular corpus preparations (threshold near 10−10 mol/l). The sensitivity to SP decreased in the sequence circular corpus —longitudinal antrum — circular antrum (threshold near 10−7 mol/l); it re-increased towards the pylorus, and in the inner pylorus was nearly as high as in the fundus. The SP responses of fundus and longitudinal corpus were purely tonic, similar to acetylcholine (ACh) and histamine (H) responses. In circular corpus, SP induced a combined phasictonic response. SP induced in antrum strips purely phasicrhythmical contractions of low frequency (similar to the H response), whereas ACh induced phasic contractions of high frequency, and in addition an increase of tone in the longitudinal antrum strips. The SP responses of the inner pylorus were not uniform; in some preparations purely tonic contractions were observed, and large phasic fluctuations of low frequency occurred in others. The phasic components of all the responses were completely suppressed by nifedipine (10−6 mol/l). Tetrodotoxin as well as blockade of adrenoceptors, of ACh and of H receptors had no effect on the SP responses. Comparative studies with preparations from guinea-pig showed that species differences exist in the SP responses of gastric muscle.

Rhythmische Dehnung der glatten Muskulatur vom Blinddarm des Meerschweinchens

SummaryThe tension development of the isolated taenia coli of the guinea-pig was measured during induced sinusoidal changes of length. (Stretch frequencies between 0.6 and 100 per min, stretch amplitude usually between 5 and 15% of the average length.)1. During continuous variation of stretch frequency over the whole range the amplitude of the tension development shows big changes. There are two marked “resonance” frequencies, at which the tension follows the rhythmic stretch regularly with maximal amplitude.2. The first resonance occurs at 35–55 per min. It depends neither on the degree of average stretch nor on the stretch amplitude. Thus it is possible to determine an intrinsic frequency of the muscle which is valid over the whole physiological range of length.3. The second resonance occurs at 0.5–3 per min. This frequency indicates an optimum for periodic tetanic activity of the tissue.4. The average tension development of the muscle during variation of stretch frequency changes in parallel with the tension amplitude except at very low frequencies.5. The results suggest that there exists a mechanical coupling mechanism between the muscle units which may play a role in synchronization.6. The preferred frequency of the taenia coli in the slow range is similar to that of other smooth muscle organs such as blood vessels.

Mechanical activity and force-frequency relationship of isolated mouse papillary muscle: effects of extracellular calcium concentration, temperature and contraction type

Abstract. Cardiac physiology of the mouse is becoming increasingly important because the mouse is the mammalian model animal of choice for genetic modifications. However, mouse cardiac muscle is still poorly characterized under physiological conditions and inconsistent results have been published in the literature regarding mechanical activity especially the force–frequency relationship in isolated mouse muscle preparations. In this study we investigated systematically several mechanical parameters of isolated mouse papillary muscle such as force–frequency relation, twitch force, time to peak tension, relaxation time and post-rest potentiation at different experimental conditions. Extracellular calcium concentration ([Ca2+]) was varied between 1.0 and 5.0xa0mM, temperature between 27°C and 37°C and force measurements were performed under isometric as well as auxotonic conditions. The mechanical activity of muscle preparations was found to be strongly dependent on [Ca2+] and temperature and slightly on contraction type. At low temperature and low [Ca2+] the force–frequency relation was strongly positive whereas at high temperature and high calcium it turned negative. The results of this study demonstrate a flat force–frequency relation in mouse papillary muscle at physiological conditions (37°C, [Ca2+] of 1.5xa0mM) and provide a reliable experimental basis for comparative studies with genetically altered mice.

Effects of gastrin-releasing peptide (GRP) on the mechanical activity of the human ileocaecal region in vitro.

Mechanical activity was recorded in muscle preparations isolated from the human ileocaecal region. Gastrin‐releasing peptide (GRP, 10−9− 10−7u2008molu2008L−1) produced two types of response in the different muscle layers. Longitudinally cut strips showed a concentration‐dependent increase in the rhythmic activity, whereas the circularly orientated layers generally reacted with a small decrease in tone. These effects could not be influenced by blockade of adrenergic or cholinergic receptors or nerve blockade with tetrodotoxin (TTX). Application of pentagastrin did not mimic the action of GRP. These findings suggest a direct action of GRP on smooth muscle via distinct receptors which have already been demonstrated to exist in human gastrointestinal tract. The opposite effects on circular and longitudinal strips might indicate a modulatory role of GRP in the control of ileocolonic transit.

Sucrose-gap technique with pressed-rubber membranes.

SummaryA sucrose-gap chamber is described which is particularly suitable for measuring potential changes in large smooth muscle preparations, of length about 20 mm and cross-sectional area up to 1 mm2. The sucrose section of the measuring canal is separated from the Krebs and KCl solutions by rubber membranes with a central hole whose diameter can be regulated by concentric pressure on the rubber membrane. Liquid junction potentials between the different solutions can thereby be eliminated. Tests with taenia coli and stomach muscle from the guinea-pig have shown that the values obtained for membrane potential and slow potential fluctuations approximate closely to those obtained by intracellular measurements. In addition, good stability was found in long-term recordings.

Phasic and Tonic Contraction Processes in the Gastrointestinal Tract

The contraction mechanisms of GI smooth muscle can be differentiated with the aid of blockers of the voltage-controlled calcium channel (e.g. nifedipine). On the one hand, nifedipine-sensitive processes produce predominantly phasic-rhythmical contractions which can merge to sustained tonic activation, called tetanic tone, and which are combined with spike discharges and calcium influx. On the other hand, nifedipine-resistant and electrically silent processes produce a specific tone. The cooperation of both processes in one and the same cell leads to a great diversity of patterns of smooth muscle activity. Specific tone dominates in regions with reservoir function and contributes significantly to the contractions of GI sphincters, with great differences between sphincter types, the various species, and, in man, also between individuals.