Tracks of marten (Martes americana), lynx (Felis lynx), red fox (Vulpes vulpes), ermine (Mustela erminea), snowshoe hare (Lepus americanus), and red squirrel (Tamiasciurus hudsonicus) were censused from 1980 to 1985 on 1-km transects in uncut stands and on eight sites that had been clear-cut between 1 and 33 years ago, in boreal mixedwood habitat near Manitouwadge, Ontario. Marten tracks were more common in uncut areas than in younger stands. Lynx tracks were most abundant on sites that were logged 20–30 years ago and were absent in uncut areas and stands less than 5 years old. Counts of red fox tracks were lowest in uncut stands and showed no consistent pattern among years of our survey with respect to stand age in second-growth forest. Hare tracks were most abundant in 20- and 30-year-old stands, and least abundant in stands less than 5 years old. Red squirrels were most common in uncut areas, but similar high values were also found in 20- and 30-year-old sites during 3 years when populations in the area were depressed. No selection of stands by age was seen for ermine. Numbers of tracks were significantly correlated with live captures of marten, hare, and red squirrels. Our results suggested that track abundance can be used as an index of habitat preferences and population trends. Highest counts were achieved in December for marten, red squirrel, and ermine, likely as a result of several types of over-winter mortality and inactivity in cold weather, which may have reduced counts in January and March. As a result of high and nonhomogeneous variance among transects and years, nonparametric statistical analysis was required. Transect length for fox and lynx should be substantially longer than 1 km (probably 3–5 km) to avoid numerous zero results.

Summary1. 4-Hydroxypropranolol, a metabolite produced after oral administration of propranolol, has been shown to be a /3-adrenoceptor blocking drug. It is of similar potency to propranolol in antagonizing the effects of isoprenaline on heart rate and blood pressure in cats and against isoprenaline protection of guinea-pigs from bronchospasm. It is not cardioselective. 2. In rats depleted of catecholamine 4-hydroxypropranolol produced an increase in heart rate, suggesting that it has intrinsic sympathomimetic activity. 3. In anaesthetized dogs 4-hydroxypropranolol produced a decrease in heart rate and dP/dt and an increase in A-V conduction time at doses within the range 0 09-1 25 mg/kg. These effects are a result of /3-adrenoceptor blockade. In dogs depleted of catecholamines these same doses produced an increase in heart rate and dP/dt and a decrease in A-V conduction time. These responses were antagonized by propranolol, and were due to the intrinsic sympathomimetic activity of the compound. At higher doses (5-25 and 13'25 mg/kg) a further dose dependent decrease in heart rate and dP/dt and an increase in A-V conduction time occurred. This trend was also seen in animals depleted of catecholamines. These changes represent membrane stabilizing activity of 4-hydroxypropranolol.4. 4-Hydroxypropranolol is a potent /8-adrenoceptor blocking drug with both intrinsic sympathomimetic activity and membrane stabilizing activity.

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1. pA2 values have been obtained for propranolol, butoxamine, H35/25 and atenolol on guinea-pig isolated trachea and atria (rate) using noredrenaline (beta 1-selective), isoprenaline (non-selective) and fenoterol (beta 2-selective) as agonists. 2. pA2 values varied with the agonist used on trachea but not on atria and, therefore, trachea : atria selectivity values varied with the agonist used. 3. It is suggested that the best estimate of the selectivity of an antagonist between beta 2- and beta 1-adrenoceptors is obtained by comparing its pA2 value obtained on trachea using a beta 2-selective agonist with that obtained on atria using a beta 1-selective agonist. The reasons for this are discussed. 4. The quantitative values for beta 2 : beta 1 selectivity obtained using the above pA2 values were butoxamine 17.0 H35/25 13.5, propranolol 2.75 and atenolol 0.036, i.e. butoxamine and H35/25 were beta 2-selective, propranolol was non-selective and atenolol was beta 1-selective. 5. The results support the hypotheses that guinea-pig trachea contains a mixture of beta 1- and beta 2-adrenoceptors and that guinea-pig atria contain only beta 1-adrenoceptors.

1 Amines related in structure to either isoprenaline (catechol series) or orciprenaline (resorcinol series) were examined for activity on isolated trachea (relaxation), atria (chronotropic action) and perfused hind-limb (vasodilatation) of the guinea-pig. 2 Compounds with a resorcinol nucleus were less potent on all three preparations but more selective for trachea than were compounds with a catechol nucleus. 3 In both catechol and resorcinol compounds potency on trachea was enhanced by and selectivity for trachea was favoured by substitution of a p-OH phenyl group in the N-isopropyl, or by replacement of the N-isopropyl with an N-t-butyl, with or without a p-OH phenyl group. 4 Most of the compounds, particularly the resorcinols, had much lower potencies, relative to isoprenaline, on hind-limb than on trachea. 5 Some of the problems associated with the quantitative measurement of selectivity and with sub-classification of,-adrenoceptors are discussed.