ABSTRACT
A taxonomic inventory of oribatid mites from lenga forests in Patagonia Argentina was carried out to assess the taxonomic diversity and to increase the knowledge of their distribution. Nine new records of soil oribatid mites from Argentina are reported. Those species were collected in Chubut province and Tierra del Fuego province. The new registered species belong to the genera Lamellozetes, Hermannia (Phyllhermannia), Crotonia, Kokoppia, Acutoppia, Lanceoppia (Baioppia), Loboppia, Membranoppia(Membranoppia) and Graptoppia (Stenoppia).
Subject(s)
Mites , Animals , Argentina , Forests , SoilABSTRACT
The effects of pacing frequency, overdrive duration and stimulus amplitude on the sinus node recovery time (SNRT) were studied in the isolated right atrium of the rat. A positive relationship between pacing frequency and the SNRT was observed, whereas overdrive duration and stimulus amplitude did not affect SNRT. There was no significant interaction among the factors studied. The effect of frequency upon SNRT probably does not involve neurotransmitter release due to stimulation, since in vitro pretreatment with atropine plus propranolol does change the SNRT-frequency relation.
Subject(s)
Cardiac Pacing, Artificial , Myocardial Contraction , Sinoatrial Node/physiology , Animals , Atrial Function , Atropine/pharmacology , Electrophysiology , Male , Neurotransmitter Agents/metabolism , Propranolol/pharmacology , Rats , Rats, Inbred StrainsABSTRACT
The effects of pacing frequency, overdrive duration and stimulus amplitude on the sinus node recovery time (SNRT) were studied in the isolated right atrium of the rat. a positive relationship between pacing frequency and the SNRT was observed, whereas overdrive duration ans stimulus amplitude did not affect SNRT. There was no significant interaction among the factors studied. The effect of frequency upon SNRT probably does not involve neurotransmitter release due to stimulation, since in vitro pretreatment with atropine plus propranolol does change the SNRT - frequency relation
Subject(s)
Rats , Animals , Cardiac Pacing, Artificial , Heart Rate , In Vitro Techniques , Sinoatrial Node/physiology , Heart Atria/physiologyABSTRACT
Peak current defibrillation thresholds (PCDT), i.e., values with 50% probability of success, were determined after ligation of the left anterior descending coronary artery (LADCA) while, simultaneously, body temperature was slowly decreased until central venous temperature reached an average minimum of 22.8 degrees C (s.d. 3.1). In 14 dogs with over 166 successful defibrillations, the average time elapsed between the moment of ligation and the last defibrillation was 179.1 min. (s.d. 31.9), with an average PCDT of 53.6 mA g-1 of heart (s.d. 20.5). This value was compared by means of the unpaired Student's t test with three previous values obtained, respectively, under hypothermia with no occlusion (HNO), normo-thermia with coronary occlusion (NCO), and normothermia with no occlusion (NNO), that is, HNO 69.5 (s.d. 30.4), NCO 81.1 (s.d. 29.3), and NNO 89.5 (s.d. 32.8), all expressed in mA g-1 of heart. All three differences even after Bonferroni's correction, were statistically significant (P less than 0.3%). We concluded that, (1) defibrillation thresholds were decreased by coronary occlusion and by hypothermia, (2) the decrease due to hypothermia was greater than that due to coronary occlusion, (3) both decrements appeared as additive.
