期刊
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
卷 292, 期 6, 页码 R2312-R2317出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpregu.00873.2006
关键词
microcirculation; precapillary sphincter; skin blood flow
类别
资金
- NHLBI NIH HHS [K25-HL-070608] Funding Source: Medline
- PHS HHS [CDC-623086] Funding Source: Medline
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [K25HL070608] Funding Source: NIH RePORTER
Skin blood flow increases in response to local heat due to sensorineural and nitric oxide (NO)mediated dilation. It has been previously demonstrated that arteriolar dilation is inhibited with NO synthase (NOS) blockade. Flow, nonetheless, increases with local heat. This implies that the previously unexamined nonarteriolar responses play a significant role in modulating flow. We thus hypothesized that local heating induces capillary recruitment. We heated a portion (3 cm(2)) of the Pallid bat wing from 25 degrees C to 37 degrees C for 20 min, and measured changes in terminal feed arteriole (similar to 25 mu m) diameter and blood velocity to calculate blood flow (n = 8). Arteriolar dilation was reduced with NOS and sensorineural blockade using a 1% (wt/vol) N-nitro-L-arginine methyl ester (L-NAME) and 2% (wt/vol) lidocaine solution (n = 8). We also measured changes in the number of perfused capillaries, and the time precapillary sphincters were open with (n = 8) and without (n 8) NOS plus sensorineural blockade. With heat, the total number of perfused capillaries increased 92.7 +/- 17.9% (P = 0.011), and a similar increase occurred despite NOS plus sensorineural blockade 114.4 +/- 30.0% (P = 0.014). Blockade eliminated arteriolar dilation (-4.5 +/- 2.1%). With heat, the percent time precapillary sphincters remained open increased 32.3 +/- 6.0% (P = 0.0006), and this increase occurred despite NOS plus sensorineural blockade (34.1 +/- 5.8%, P 0.0004). With heat, arteriolar blood flow increased (187.2 +/- 28.5%, P = 0.00003), which was significantly attenuated with NOS plus sensorineural blockade (88.6 +/- 37.2%, P = 0.04). Thus, capillary recruitment is a fundamental microvascular response to local heat, independent of arteriolar dilation and the well-documented sensorineural and NOS mechanisms mediating the response to local heat.
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