Stimulating effect of thromboxane B2 on isolated rat atria

Summary Thromboxane B₂ enhanced the beating frequency and the contractile tension of isolated rat atria. Both effects were inhibited by propranolol, by pretreatment with 6-hydroxydopamine, or after inhibition of prostaglandins synthesis with indomethacin and acetylsalicylic acid.This work has been supported by grant 6638 from CONICET (Argentina).     

Protein synthesis inhibition induced by dimethylnitrosamine and diethylnitrosamine on isolated rat hepatocytes

Summary Time- and dose-dependent protein synthesis inhibition takes place following exposure to high doses of dimethylnitrosamine (DMN) or diethylnitrosamine (DENA) in isolated rat hepatocytes. The ability of DENA to depress protein synthesis is 5-fold higher than that of DMN. Cells inhibited by 60 min exposure to DMN or DENA, and then incubated in a nitrosamine-free medium, regain their initial rate of protein synthesis. This recovery is faster and more complete for DENA-treated cells.     

Postnatal development of adrenergic and cholinergic sensitivity in the isolated rat atria

Summary The sensitivity to adrenergic drugs in isolated rat atria increased with the postnatal development. The cholinergic chronotropic sensitivity did not further change after birth.     

Postnatal development of adrenergic and cholinergic sensitivity in the isolated rat atria

The sensitivity to adrenergic drugs in isolated rat atria increased with the postnatal development. The cholinergic chronotropic sensitivity did not further change after birth.     

The effects of oxamate on the contractility of isolated rat atria

Zusammenfassung Oxamat, das die Lactat-Dehydrogenase hemmt, erniedrigt die Kontraktionsfähigkeit des Vorhofs mit und ohne Anwesenheit von Glucose im Medium und bei Hinzufügung von 2-DG oder Atropin. Hohe Konzentration von Pyruvat erhöht die Depression von Oxamat auf den Vorhof im Glucose-Milieu. Oxamat sensibilisiert das Gewebe für funktionellen Abbau durch Glycolyse.

---

---

This research was supported by grants No. 1441 and No. HE-994801 from Consejo Nacional de Investigaciones de la República Argentina, and from the National Institute of Health, respectively.

---

Research Fellow from the Consejo Nacional de Investigaciones de la República Argentina.

---

Established Investigator from the Consejo Nacional de Investigaciones de la República Argentina.     

Protein synthesis inhibition induced by dimethylnitrosamine and diethylnitrosamine on isolated rat hepatocytes.

Time- and dose-dependent protein synthesis inhibition takes place following exposure to high doses of dimethylnitrosamine (DMN) or diethylnitrosamine (DENA) in isolated rat hepatocytes. The ability of DENA to depress protein synthesis is 5-fold higher than that of DMN. Cells inhibited by 60 min exposure to DMN or DENA, and then incubated in a nitrosamine-free medium, regain their initial rate of protein synthesis. This recovery is faster and more complete for DENA-treated cells.     

Effect of nicotine on the transmembrane potential and contractility of isolated rat atria

Zusammenfassung Die Wirkungen von Nikotin auf die Kontraktilität und die Membranpotentiale des Rattenatriums wurden untersucht. Nikotin (5 × 10^–4 M) erhöhte gleichzeitig die entwickelte Spannung sowie die Dauer und Fläche des Aktionspotentials. Ein möglicher Zusammenhang dieser Änderungen mit der erhöhten Kontraktilität wird diskutiert.

---

---

Deceased 22 July 1966.     

Protein synthesis stimulation in rat liver by chloroquine

Riassunto L'inoculazione endoperitoneale di Clorochina, a dosi comprese tra 15 e 45 mg/kg di peso corporeo determina una stimolazione precoce delle sintesi proteiche nel fegato di ratto. Questa azione non é correlata ad un aumento della sintesi di RNA, né appare conseguente ad una stimolazione corticosurrenalica. L'effetto osservato é brevemente discusso sulla base delle note interazioni tra lisosomi e Clorochina.     

Chronic exercise does not alter the chronotropic response of isolated rat atria to catecholamines

Summary Atria isolated from rats after 7 weeks of exercise training beat at a slower rate than did atria from sedentary controls. There is no significant difference between the chronotropic responses of the 2 groups to epinephrine or morepinephrine.This study was supported in part by a grant from the Genesee Valley Heart Association.     

Effect of exercise training on the chronotropic response of isolated rat atria to atropine

Summary Atria isolated from rats after 7 weeks of exercise training beat at a slower rate than did atria from sedentary controls. Atria from exercised rats showed a significant acceleration in response to atropie.This study was supported by a grant from the Genesee Valley Heart Association.     

Effects of anoxia on excitability,refractoriness, and contractility in isolated rabbit atria

Zusammenfassung An der isolierten Kaninchenherzvorkammer verursacht Sauerstoffmangel Verminderung der diastolischen Erregbarkeit, Verlängerung der refraktären Phase sowie Herabsetzung der Kontraktionsfähigkeit. Herzmuskelflimmern wurde während dieser Anoxie nicht beobachtet. Sauerstoffzufuhr führte zu einer vollständigen Aufhebung der Anoxieauswirkung auf die absolute Refraktärperiode, zu einer teilweisen Aufhebung dieser Auswirkungen auf die Dauer der refraktären Gesamtpause, die diastolische Erregbarkeit und das Kontraktionsvermögen.     

Electrical and contractile properties of isolated rat atria in buffer-free medium as influenced by changes in pH

Zusammenfassung Der Einfluss von pH-Änderungen auf die Kontraktions- und elektrischen Eigenschaften von Rattenvorhöfen wurde in pufferfreien Medien untersucht; eine Suspension von Vorhöfen in pufferfreier Krebs-Ringerlösung hatte eine zweiphasige inotrope Wirkung, (anfängliche Erregung, hierauf progressive Entspannung). Reduktion des pH von 7,4 auf 6 hatte keine bedeutende Wirkung auf die kontraktile Spannung, während eine Erhöhung des pH von 7,4 auf 8,8 das Spannungsdekrement verringerte. Saures Medium erhöhte die Dauer der Aktionspotentiale, verringerte die maximale Geschwindigkeit der Depolarisierung und verlängerte die Leitungszeit, während ein alkalisches Medium die Dauer der Aktionspotentiale verkürzte.

---

---

This work was supported by Research grants (No. 5T1HE-5536 and H-1999) from the National Heart Institute, U.S. Public Health Service.

---

Established investigator from the Consejo Nacional de Investigaciones Cientificay y Técnicas de la República Argentina.     

An adrenergic participation subserving a positive inotropism and chronotropism of prostacyclin on isolated rat atria

Summary The effects of prostacyclin (PGI₂) on the contractile frequency and on the isometric developed tension of spontaneously beating or paced isolated rat atria were explored. PGI₂ enhanced frequency and contractile tension, both effects being blocked by the presence of propranolol, or following a pretreatment with 6-OHDopamine.This work has been supported by Grant 6638 from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina.