ß-Adrenergic receptor blockade does not modify non-thermal sweating during static exercise and following muscle ischemia in habitually trained individuals.

PURPOSE: This study investigated the influence of ß-adrenergic receptor blockade on sweating during bilateral static knee extension (KE) and lateral isometric handgrip (IH) exercises followed by post-exercise muscle ischemia (PEMI) in habitually trained individuals. METHOD: Ten habitually trained men (maximum oxygen uptake, 57.1 ± 3.4 ml kg-1 min-1) were mildly heated by increasing their skin temperature, and bilateral KE or lateral IH exercises at an intensity of 60% maximum voluntary contraction were subsequently performed for 1 min, followed by PEMI to stimulate muscle metaboreceptors for 2 min. Sweat rates were measured on the bilateral forearms (KE) or thighs (IH) transdermally administered with 1% propranolol (propranolol, a non-selective ß-adrenergic receptor inhibitor) or saline (control) via iontophoresis. RESULTS: Relative to the pre-exercise baseline values, IH exercise (P = 0.038) followed by PEMI (P = 0.041) similarly increased sweat rates on the thighs at both control and propranolol sites (baseline, 0.05 ± 0.04 vs. 0.05 ± 0.04; IH, 0.14 ± 0.12 vs. 0.15 ± 0.14; PEMI, 0.14 ± 0.16 vs. 0.14 ± 0.16 mg cm-2 min-1). KE increased sweat rates on the forearms (P = 0.001) at both control and propranolol sites similarly (baseline, 0.02 ± 0.03 vs. 0.02 ± 0.03; KE, 0.21 ± 0.19 vs. 0.20 ± 0.18), whereas PEMI did not significantly induce sweating at these sites (P = 0.260) (0.09 ± 0.12 and 0.10 ± 0.12 mg cm-2 min-1, respectively). CONCLUSION: These results suggest that non-thermal drives induced by static exercise and PEMI do not elicit ß-adrenergic sweating in habitually trained individuals even when the non-thermal drives are originated from leg(s) under the conditions in the present study.

Newly formed dust within the circumstellar environment of SN Ia-CSM 2018evt.

Dust associated with various stellar sources in galaxies at all cosmic epochs remains a controversial topic, particularly whether supernovae play an important role in dust production. We report evidence of dust formation in the cold, dense shell behind the ejecta-circumstellar medium (CSM) interaction in the Type Ia-CSM supernova (SN) 2018evt three years after the explosion, characterized by a rise in mid-infrared emission accompanied by an accelerated decline in the optical radiation of the SN. Such a dust-formation picture is also corroborated by the concurrent evolution of the profiles of the Hα emission line. Our model suggests enhanced CSM dust concentration at increasing distances from the SN as compared to what can be expected from the density profile of the mass loss from a steady stellar wind. By the time of the last mid-infrared observations at day +1,041, a total amount of 1.2 ± 0.2 × 10-2 M⊙ of new dust has been formed by SN 2018evt, making SN 2018evt one of the most prolific dust factories among supernovae with evidence of dust formation. The unprecedented witness of the intense production procedure of dust may shed light on the perceptions of dust formation in cosmic history.