In isolated spontaneously beating atria of rabbits, tetrandrine (Tet) and verapamil (Ver) shifted the concentration-rate curves to isoproterenol (Iso) to the right in a non-parallel manner and depressed their maxima. (±)-propranolol behaved as a competitive β-adrenoceptor antagonist.
The pD’2 values of Tet and Ver were 6.48 ± 0.45 and 4.30 ± 0.18, respectively. Hence the antagonistic effect of Ver was stronger than that of Tet. The pA2 of propranolol = 7.86 ± 0.21.
Tet and Ver antagonized the positive chronotropic responses to Ca++ (3.3 mM) in spontaneously beating rabbit atria.
It is proposed that Tet is a calcium antagonist similar to Ver. Its inhibitory effect on the tachycardia induced by Iso is due to its action in Ca++ which may be an essential modulator of the sequence of events linking β-adrenoceptor activation and heart rate response.
The isolated rat uterus contraction induced by oxytocin and Ca+ + after high-K depolarization were markedly inhibited by tetrandrine (Tet). The depression was immediately reversed by addition of Ca++ to the bath fluid. Tet and verapamil (Ver), which shifted the cumulative dose-response curves to the right and depressed the maximal responses to CaCl2 acted as non-competitive antagonists. The oxytocin-induced Ca++-dependent contractions were depressed by 4.8 and 30 μM Tet. Tet 30 μM also inhibited the Ca++o-dependent component of the contraction.
The effect of Ver on isolated rat uterus was stronger than that of Tet. But up to 0.05 μM, it showed no effect on Ca+ +-dependent oxytocin contraction.
These results indicate that Tet is an effective Ca+ +-antagonist very similar to Ver on isolated rat uteri.
The effects of tetrandrine (Tet) on action potential and contraction were studied in isolated guinea pig papillary muscles in normal and K+-rich Tyrode’s solution.
Tet produced concentration-dependent negative inotropic effect and shortened APD20 (action potential duration) and APD90, while resting potential and amplitude of the action potential were not affected. Thus, an excitation-contraction uncoupling was revealed. Tet decreased the amplitude of Ca++-mediated slow action potential induced by high K+. These results are in contrast with those of quinidine but are consistent with those of slow channel blockers.
Durch Abspaltung der endständigen Phosphatgruppe durch ein in Katecholaminspeichervesikeln vorhandenes Enzym wird ATP zu ADP umgewandelt. Dieses gereinigte Enzym (Fraktion I) ist ein Protein mit einem Molekulargewicht von etwa 45 000. Das Ziel dieser Untersuchung war der immunhistochemische Nachweis von F I außer in chromaffinen Zellen der Paraganglien auch in verschiedenen aminergen Geweben. Es zeigte sich, daß F I nicht auf die chromaffinen Zellen der Paraganglien beschränkt ist, sondern auch in Zellen vom System der Paraneurone, z.B. in den Zellen des Pankreasinselorgans, in enteroendocrinen Zellen und in Zellen des Plexus myentericus und Plexus submucosus des Magen-Darm-Traktes vorhanden ist. Die funktioneile Bedeutung von F I wird diskutiert.
The thyroid stimulating effect of tissue extracts was studied in rats. The serum levels of T4, T3 and cAMP content of thyroid increased significantly at 2–4th hour and then returned to the initial values at 6th hour after injection of spleen extract. After injection of placenta extract, the same levels increased markedly as well. Their stimulating effects on the thyroid system were probably independent of the response of the adrenal system. Administration of morphine prior to injection of tissue extracts blocked their stimulating effects on serum levels of T4, T3 and the cAMP content of thyroid.
The above results demonstrate that tissue extracts of spleen and placenta are capable of stimulating hypothalamo-pituitary-thyroid axis possibly via hypothalamus.
M-mode echocardiograms were studied in 40 patients with myocardial infarction. The results we obtained indicate that both EPSSa and EPSSb are very valuable indices for evaluating LV function in patients with myocardial infarction. Accuracy of EPSSb attained in this study is identical with that of EPSSa, and, in addition, the measurement of the former is simpler. Therefore, we recommend to use EPSSb instead of EPSSa in clinical practice
This paper presents our study on the composition and morphology of 56 upper urinary tract calculi with infrared spectroscopy and polarizing microscope, and our observation of the ultramicroscopic structure of calculi with scanning electron microscope. In 5 urinary calculi the nuclei were at first found to be pure calcium oxalate by X-ray diffraction and even verified by infrared spectroscopy, but later it was found that none of these 5 calculi was pure oxalate, and most of the 56 nuclei were mixed with apatite. Our preliminary viewpoint is, therefore, that at the initial stage of oxalate calculus formation the nucleation might be not homogeneous, in which apatite might play an important role.