Measurement of Heat Production in Dog Submandibular Gland

Publisher Website
Google Scholar
Abstract
In dog submandibular glands changes in metabolic heat production were measured during a secretory period induced by electrical stimulation of the chorda tympani. When measured with fine thermocouples, the temperature of both the gland itself and venous blood from the gland increased by 0.1-0.7.degree. C at the maximum. The blood flow was about 0.3 g .cntdot. min-1 .cntdot. g-1 wet wt of gland at a resting period and increased to 1-3 g .cntdot. min-1 .cntdot. g-1 at the maximum of secretory response. The resting heat production in vitro, measured by a microcalorimeter, was 3.3 mW [milliwork units] .cntdot. g-1 at 27.degree. C and 7.8 mW .cntdot. g-1 at 37.degree. C. The specific heat of the blood and the salivary gland, measured by a microcalorimeter, were 3.97 and 3.91 J .cntdot. g-1 .cntdot. .degree.C-1, respectively. The change in conductive heat loss, measured by a thermopile under stimulated conditions, ranged from 4-6 mW .cntdot. g-1 at the maximum. Metabolic heat production during secretion in vivo (37.degree. C) was estimated from temperature changes in the glandular tissue and blood, blood flow, specific heat and resting heat production. Values were in the range 15-80 mW .cntdot. g-1 at the maximum. Heat production increased rapidly within the first 20 s to reach a maximum and then declined with time, but slow heat production continued. The relation of heat production to transport of ionic substances during secretory processes was discussed.