The effect of nifedipine and verapamil on KC1-induced rhythmic contractions of guinea pig ureter in vitro

Addition of KC1 (40 mM) produced rhythmic contractions of guinea-pig ureters in vitro which were unaffected by phentolamine, atropine or tetrodotoxin. KC1 failed to elicit rhythmic contractions of ureters incubated in a Krebs solution with no added Ca++; in these conditions the addition of CaC12 in concentrations of 1.5 mM, or higher, produced rhythmic contractions whose frequency, but not amplitude, was proportional to CaC12 concentration in the bathing medium. EDTA reduced the frequency of KC1-induced rhythmic contractions without affecting their amplitude. Nifedipine and verapamil reduced both the frequency and the amplitude of KC1-induced rhythmic contraction; verapamil was more effective than nifedipine in reducing their amplitude. Urethane reduced the amplitude without significantly affecting the frequency of KC1-induced rhythmic contractions. An increase in the extracellular Ca++ concentration reverted the suppressive effect of all drugs under study. These results suggest that an influx of Ca++ from the extracellular space is responsible for the initiation of KC1-induced rhythmic contractions and is involved in the mechanism(s) which regulates their frequency, but that a separate mechanism regulates their amplitude.     

The effect of ascorbic acid on cadmium accumulation in guinea pig tissues

Accumulation of cadmium in organs of guinea pigs after subchronic oral cadmium treatment (1 mg Cd/animal/24 h) was in the following order: kidneys > liver > heart > testes > brain. The preventive effects of high doses of ascorbic acid (AA) against cadmium deposition were more pronounced in the testes, heart and brain, and in the kidney only after short-term cadmium treatment. Ascorbic acid had no protective effect on cadmium accumulation in the liver.     

Tricyclic antidepressants antagonize prostaglandin (PG) E2-induced contractions of the guinea pig ileum and hypomotility in the mouse

The interactions of PGE2 and 2 tricyclic antidepressants were tested both on the guinea pig ileum and motility in the mouse. PGE2-induced contractions of the guinea pig ileum were irreversibly blocked by amitriptyline and desipramine. Chronic administration of amitriptyline and desipramine blocked PGE2-induced hypomotility in the mouse.     

Tricyclic antidepressants antagonize prostaglandin (PG) E20induced contractions of the guinea pig ileum and hypomotility in the mouse

Summary The interactions of PGE₂ and 2 tricyclic antidepressants were tested both on the guinea pig ileum and motility in the mouse. PGE₂-induced contractions of the guinea pig ileum were irreversibly blocked by amitriptyline and desipramine. Chronic administration of amitriptyline and desipramine blocked PGE₂-induced hypomotility in the mouse.     

The histamine content of guinea pig mast cells

Zusammenfassung Von der Voraussetzung ausgehend, dass alles Histamin in den Mastzellen lokalisiert ist, wurde berechnet, dass jede Mastzelle in Aorta, Trachea, Uterus und Jejunum des Meerschweinchens 25–34 µµg Histamin-Base enthält. Die anaphylaktische Freisetzung des Histamins war proportional der Verminderung des Mastzellengehaltes und wurde zu 12–17 µµg/Mastzelle berechnet. Jejunum gab keine anaphylaktische Reaktion.     

Modification of human adenovirus type 7 after culture in guinea pig brain cells in vitro]

Multiplication of human adenovirus 7 (Ad7) is restricted in subcultures of adult Guinea Pig brain cells. It was however possible to recover enough infectious virus to purify it, and to study its properties. Several properties are similar to that of Ad 7 produced in HeLa cells but differences in sensitivity to cesium chloride and in its polypeptide composition were found.     

Effect of taurine administration on liver lipids in guinea pig

The oral administration of 0.4% taurine in drinking water for 14 consecutive days showed the following hepatic effects in male guinea pig. The percentage of tauro-conjugated biliary bile acids was increased from 17.2-54.2%; the ratio liver weight/body weight was increased, and fatty change was induced. Liver triglyceride concentration was accordingly increased; diglyceride and phosphatidylcholine concentrations were reduced by the treatment, while phosphatidylethanolamine level was not affected. These changes suggest an adverse effect of taurine administration on phosphatidylcholine hepatic synthesis.     

Effect of taurine administration on liver lipids in guinea pig

Summary The oral administration of 0.4% taurine in drinking water for 14 consecutive days showed the following hepatic effects in male guinea pig. The percentage of tauro-conjugated biliary bile acids was increased from 17.2–54.2%; the ratio liver weight/body weight was increased, and fatty change was induced. Liver triglyceride concentration was accordingly increased; diglyceride and phosphatidylcholine concentrations were reduced by the treatment, while phosphatidylethanolamine level was not affected. These changes suggest an adverse effect of taurine administration on phosphatidylcholine hepatic synthesis.     

Frequency-dependent effect of verapamil on rat soleus muscle

Summary In the presence of verapamil (0.1 mM) rat soleus muscle fibers failed to generate action potentials with overshoots. In fibers with their V_m set to a local level of –90 mV, verapamil produces a gradual reduction in the amplitude of the repetitive action potentials; this effect is more pronounced at high rates of stimulation (100 Hz). Our results suggest a local anesthetic action of this drug that could contribute with its calcium channel blocking effect to the diminished mechanical tension observed in the presence of the drug.Acknowledgments. We thank A. Losavio and M. Stefanolo for technical assistance. This work was supported by grants from CONICET and SUBCYT, Buenos Aires, Argentina and Muscular Dystrophy Association, USA.     

Frequency-dependent effect of verapamil on rat soleus muscle

In the presence of verapamil (0.1 mM) rat soleus muscle fibers failed to generate action potentials with overshoots. In fibers with their Vm set to a local level of -90 mV, verapamil produces a gradual reduction in the amplitude of the repetitive action potentials; this effect is more pronounced at high rates of stimulation (100 Hz). Our results suggest a local anesthetic action of this drug that could contribute with its calcium channel blocking effect to the diminished mechanical tension observed in the presence of the drug.     

Nerve-mediated action of forskolin on guinea pig ileal mucosa

The effects of forskolin on myenteric neuronal activity and mucosal function were examined in guinea pig ileum. Forskolin increased the excitability of myenteric neurons, and increased mucosal chloride secretion by stimulating enteric neurons as well as by acting directly on enterocytes.     

Nerve-mediated action of forskolin on guinea pig ileal mucosa

Summary The effects of forskolin on myenteric neuronal activity and mucosal function were examined in guinea pig ileum. Forskolin increased the excitability of myenteric neurons, and increased mucosal chloride secretion by stimulating enteric neurons as well as by acting directly on enterocytes.Acknowledgment. The authors thank E. Martens, S. Bowen for technical assistance and N. Schaad for secretarial assistance. This work was supported by National Institutes of Health Grants, F32-AM07301, K-104-AM1004, RO1-AM29699, RO1-AM26742 and an Eloise Gerry Fellowship.     

The effect of toxin II isolated from sea anemones (Anemonia sulcata) on the isolated guinea pig ileum]

When the guinea-pig isolated ileum is treated with the Toxin II from Anemonia sulcata, it releases not only acetylcholine but also serotonin. These transmitters are both involved in the spasmogenic action of the toxin.     

The effect of verapamil and dibutyrul cAMP on the spontaneous activity of the sinus node

Summary Verapamil stops the electrical activity of the sinus node cells. In the presence of verapamil, dibutyryl cAMP brings about a recovery of the spontaneous activity, whereas noradrenaline is ineffective.     

The effect of noradrenaline on heat production in the new-born pig

Résumé La production de chaleur, la température du corps et du QR de 6 porcelets âgés de 4 à 13 jours, avant et après l'injection s.c. de noradrénaline (200 g/kg) ont été déterminées. On n'a pas constaté l'effet de l'injection de noradrénaline sur les animaux de 4–6 jours, pendant que le métabolisme et la température du rectum des porcelets âgés de 11–13 jours augmentaient distinctement, et que la valeur du QR a baissait significativement.

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The authors are indepted to Dr.Maria Kotarbiska-Urbaniec for the provision of experimental animals.     

Thermoadaptive influence on reactivity pattern of vasopressinergic neurons in the guinea pig

In cold-adapted guinea pigs, increased amounts of arginine-vasopressin (AVP) immunoreactive material could be visualized in neurons of the supraoptic and paraventricular nucleus, in fibers projecting to the neurohypophysis and in fiber terminals in the ventral lateral septum and in the amygdala. In warm-adapted animals the reactivity to AVP antiserum was poor in all neuronal structures examined. High AVP-immunoreactivity was accompanied by a reduced febrile response to bacterial pyrogen in cold-adapted guinea pigs.     

Thermoadaptive influence on reactivity pattern of vasopressinergic neurons in the guinea pig

Summary In cold-adapted guinea pigs, increased amounts of arginine-vasopressin (AVP) immunoreactive material could be visualized in neurons of the supraoptic and paraventricular nucleus, in fibers projecting to the neurohypophysis and in fiber terminals in the ventral lateral septum and in the amygdala. In warm-adapted animals the reactivity to AVP antiserum was poor in all neuronal structures examined. High AVP-immunoreactivity was accompanied by a reduced febrile response to bacterial pyrogen in cold-adapted guinea pigs.