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  • Isolated ciliary muscle strips  (1)
  • Schlüsselwörter Myokardiale Laserrevaskularisation – Angina pectoris – koronare Herzerkrankung  (1)
  • 1
    ISSN: 1432-2013
    Keywords: Ciliary muscle ; Cell culture ; Intracellular calcium ; Isolated ciliary muscle strips ; Contractility ; Acetylcholine ; Carbachol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electromechanical and pharmacomechanical coupling was investigated in human ciliary muscle by measuring the intracellular free calcium in single cultured ciliary muscle cells and the contractility in meridional ciliary muscle strips. The basal resting calcium concentration was 75±8.7 nmol/l, n=23. Application of acetylcholine (0.1 mmol/l) and carbachol (0.1 mmol/l) resulted in an initial [Ca2+]i peak followed by a recovery phase and a [Ca2+]i plateau. The initial [Ca2+]i peak was still observed in the absence of extracellular calcium and in the presence of verapamil (0.1 mmol/l). During its plateau [Ca2+]i was decreased by withdrawal of extracellular calcium or application of verapamil (0.1 mmol/l). Depolarization induced by a high level of extracellular potassium yielded only a small transient [Ca2+]i peak without a [Ca2+]i plateau. In isolated ciliary muscle strips, muscarinic stimulation (carbachol 0.1 mmol/l) resulted in an initial phasic and a subsequent tonic contraction. Removal of external calcium reduced the phasic contraction to 30.6±4.4% (n=8) and completely abolished the tonic one. Verapamil (0.1 mmol/l) had only a slight relaxing effect when applied during the tonic contraction. We conclude that human ciliary muscle contraction is mediated by calcium release from intracellular stores and calcium entry through calcium channels, which are most probably receptor-operated. Depolarization of the muscle cell membrane and calcium entry through voltage-operated calcium channels do not contribute significantly to human ciliary muscle contraction.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1285
    Keywords: Key words Myocardial laser-revascularization – angina pectoris – coronary artery disease ; Schlüsselwörter Myokardiale Laserrevaskularisation – Angina pectoris – koronare Herzerkrankung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei Patienten mit schwerer Angina pectoris aufgrund einer koronaren Herzerkrankung, bei denen aufgrund der Koronarmorphologie oder vorausgegangener Interventionen keine Möglichkeit einer Ballondilatation oder einer Bypassoperation mehr besteht, kann die klinische Symptomatik und die körperliche Belastbarkeit häufig durch eine transmyokardiale Laserrevaskularisation (TMR) gebessert werden. Ein Nachteil der TMR ist die Notwendigkeit eines chirurgischen Zugangs zum Herzen, um die Kannäle vom Epikard aus in das Myokard einzubringen. Daher wurde ein Kathetersystem entwickelt, mit dem die Laserkanäle vom linksventrikulären Kavum aus in das Myokard eingebracht werden können. Bisher wurden am Herzzentrum Leipzig 85 Patienten mit therapierefraktärer Angina pectoris mit dieser perkutanen myokardialen Laserrevaskularisation (PMR) behandelt. Bei 43 Patienten wurde nur eine Region des Herzens (anterior, lateral, inferior oder septal) behandelt, bei 42 Patienten wurden während einer PMR-Sitzung zwei oder drei Regionen des Herzens behandelt. Hierbei wurden 12.3±4.3 (Bereich 4–22) Laserkanäle je Myokardregion eingebracht. Sechs Monate nach PMR war bei der überwiegenden Zahl der Patienten eine deutliche Verbesserung der klinischen Symptomatik (CCS-Klasse vor PMR: 3,3±0,4, nach 6 Monaten: 1,6±0,9) (p 〈 0,001) und eine Steigerung der körperlichen Belastbarkeit (vor PMR: von 349±138 s, nach 6 Monaten: 470±193 s) (p 〈 0,05) eingetreten, szintigraphisch ließ sich jedoch eine Verbesserung der myokardialen Perfusion jedoch bisher nicht nachweisen. Somit scheint die PMR eine sichere und mit einem vertretbaren Aufwand durchführbare neue Therapiemethode für Patienten mit schwerer Angina pectoris im Endstadium einer koronaren Herzerkrankung ohne konventionelle Revaskularisierungsmöglichkeiten zu sein. Die ersten Ergebnisse deuten auf eine Verbesserung der klinischen Symptomatik und eine gesteigerte Belastbarkeit der Patienten hin, eine verbesserte myokardiale Perfusion nach PMR konnte jedoch bisher noch nicht nachgewiesen werden.
    Notes: Summary In patients with severe angina pectoris due to coronary artery disease, who are not candidates for either percutaneous coronary angioplasty or coronary artery bypass surgery, transmyocardial laser revascularization (TMR) often leads to improvement of clinical symptoms and increased exercise capacity. One drawback of TMR is the need for surgical thoracotomy in order to gain access to the epicardial surface of the heart. Therefore, a catheter-based system has been developed, which allows creation of laser channels into the myocardium from the left ventricular cavity. Between January 1997 and November 1999, this “percutaneous myocardial laser-revascularization” (PMR) was performed in 85 patients at the Herzzentrum Leipzig. In 43 patients, only one region of the heart (anterior, lateral, inferior or septal) was treated with PMR; in 42 patients two or three regions were treated in one session. 12.3±4.3 (range 4–22) channels/region were created into the myocardium. Six months after PMR, the majority of patients reported significant improvement of clinical symptoms (CCS class at baseline: 3.3±0.4; after 6 months: 1.6±0.9) (p 〈 0.001) and an increased exercise capacity (baseline: 349±138 s; after 6 months: 470±193 s) (p 〈 0.05); however, thallium scintigraphy failed to show increased perfusion in the PMR treated regions. PMR seems to be a safe and feasible new therapeutic option for patients with refractory angina pectoris due to end-stage coronary artery disease. The first results indicate improvement of clinical symptoms and increased exercise capacity; evidence of increased perfusion in the laser-treated regions is still lacking.
    Type of Medium: Electronic Resource
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