Hemodynamic Function during Neurectomy in Halothaneanesthetized Horses with or without Constant Dose Detomidine Infusion

Nine horses were premediated with acepromazine, and anesthesia was induced with guaifenesin and thiamylal. Anesthesia was maintained in four horses with halothane in oxygen, and in five horses with halothane in oxygen plus a constant dose infusion of detomidine. Both maintenance regimens produced a MAC equivalent of 1.4 at the ambient barometric pressure. Hemodynamic and respiratory measurements were made after the horses were anesthetized, during surgical manipulations involving skin or tissues other than nerves, during manipulation and transection of digital nerves, and after surgery while the limbs were being bandaged. Heart rate was significantly higher in horses anesthetized with halothane only than in horses that also received detomidine; there were no other differences in hemodynamic function or recovery characteristics. Respiratory rate was significantly higher than baseline during soft tissue and nerve manipulations; arterial blood pressure was significantly higher after surgery began and highest during neurectomy; cardiac output and cardiac index were significantly decreased during surgery; systemic vascular resistance was significantly increased during neurectomy and bandaging and highest during neurectomy. The data suggest that the increase in blood pressure often associated with surgical stimulation is caused by increased vascular resistance and may be accompanied by a decrease in cardiac output.     

LABORATORY EXPERIMENTS ON 'CUT BARK' TREATMENTS WITH HERBICIDES, USING CUTTINGS OF POPULUS EURO AMERICAN A'I-78'

Summary. A laboratory method is described for studying the effects of introducing herbicides into the vascular tissues oi Populus cuttings. Of sixteen herbicides tested in this way, MCPA and picloram were the most phytotoxic. Ester formulations of growth regulator herbicides were less active than water soluble amine or inorganic salts. The phytotoxic effects of the latter were increased by supplying water to the cuttings before or after treatment or by applying the herbicide in a relatively large volume of water. A non-ionic surfactant did not increase the effects of injected MCPA salt, approximately similar amounts of which moved both upwards and downwards in cuttings from the point of introduction.
Expériences en laboratoire sur des boutures de Populus × euroamericana "I-78" traités avec des herbicides     

Effect of ammonium sulphate and related salts on the phytotoxicity of dichlorprop and other herbicides used for broadleaved weed control in cereals

In glasshouse experiments, additions of 10–100 g 1^?1 ammonium sulphate enhanced the phytotoxicity to broadleaved weeds and cereals of several water-soluble herbicides applied post-emergence in 75–300 1 ha^?1 with hydraulic nozzles. Studies with dichlorprop potassium salt and chickweed Stellaria media (L.) Vill. examined interactions between ammonium sulphate and environmental, application and formulation factors. Simulated rainfall immediately after spraying greatly reduced dichlorprop activity, whether or not ammonium sulphate was present. However, when there was an interval of 2–24 h between spraying and rainfall, the additive increased phytotoxicity. Surfactants tended to reduce dichlorprop phytotoxicity to Stellaria media, both in the presence and absence of ammonium sulphate. Certain other inorganic salts including sodium sulphate also enhanced phytotoxicity. Applications by rotary atomizer in very low spray volume (15 1 ha^?1, 250–280 μm drops) were less effective than conventional 150 1 ha^?1 applications. When very low volume application was used, addition of ammonium sulphate or nitrate tended to reduce activity further. In the field, ammonium sulphate significantly increased the effects against weeds of a commercial dichlorprop potassium salt formulation applied conventionally in 200 1 ha^?1 spray volume. Neutralized phosphoric acid had a similar effect but a mixture of this additive and ammonium sulphate reduced phytotoxicity. Both additives slightly increased dichlorprop injury to barley.