Relationship of hairless mouse skin surface temperature to wound severity and maturation time.

Skin surface temperature (SST) changes measured on live hairless mice are presented as a simple means of following wound healing. SST is generally determined by 3 factors which are the ambient temperature, the rate of water loss from the surface of the skin and the diffusion of thermal energy from the body's core. The SST increase immediately after a burn injury reflects the amount of thermal energy absorbed by the skin surface. For burns and other injuries, the drop in SST following injury, but after thermal equilibrium has been established, provides an early indication of the degree of impairment of the skin's barrier. Three kinds of mouse skin wounds, mechanical (tape stripping), thermal and chemical (phenol application), were investigated. SST nadirs ranged from 2.1 to 4.4 degrees C with mild to full-thickness burns, respectively. Except for the earliest moments after wounding, striking parallels were noted between SST and transepidermal water loss profiles for these injuries. The SST profile over the full course of wound healing clearly indicates the severity of the injury, the stages of wound maturation and the time to complete skin healing.

Androgenic effects on angiotensin II-induced blood pressure and cochlear blood flow changes in rats.

Ovariectomized, castrated, and sham-castrated rats pretreated with oil or testosterone were intra-arterially infused with saline and three doses of angiotensin II while blood pressure and cochlear blood flow were measured. The results indicated a positive dose-response relationship for blood pressure and cochlear blood flow. Sham-castrated males had higher mean blood pressure responses than castrated males, followed by ovariectomized females. Cochlear blood flow responses were higher in the sham-castrated males than the ovariectomized females, followed by the castrated males. In comparison to the male groups, the ovariectomized females evidenced the lowest, middle, and highest cochlear blood flow responses to the three increasing doses of angiotensin II. Testosterone pretreatment facilitated angiotensin-induced cochlear blood flow elevations in all three angiotensin doses. These results suggest that endogenous and exogenous androgens may alter blood pressure and/or cochlear blood flow responses to angiotensin II via different mechanisms.

The effects of intracerebroventricularly administered angiotensin II on blood pressure and cochlear blood flow in rats and guinea pigs.

Guinea pigs and Sprague-Dawley rats were intracerebroventricularly (icv) infused with various doses of angiotensin II (AII) in order to investigate central control of and species differences in cochlear blood flow (CBF) and blood pressure (BP). The results indicated a positive dose-response relationship between icv infusions of AII for BP and CBF in members of both species. This relationship was more predictable in the guinea pig than in the rat. In addition, responses to similar AII doses between species indicated that: a) BP elevations were significantly greater in the rat than in the guinea pig, b) CBF elevations were not significantly different between the rats and guinea pigs, and c) CBF was more highly correlated with BP in the guinea pig than in the rat. These results suggest that different relationships may exist between BP and CBF in rats and guinea pigs.

Blood pressure in resting, anesthetized and noise-exposed guinea pigs.

This study investigated blood pressure in guinea pigs while they were 1) alert and free moving, 2) anesthetized with different anesthetics, and 3) exposed to continuous, 115 dB SPL white noise under anesthesia. The animals were prepared with a carotid artery catheter and permitted to recover for 48 h before blood pressure levels were measured. Mean arterial blood pressure in the resting, unrestrained guinea pig was 64 mmHg (+/- 1.38 S.E.). Ketamine Hydrochloride (Ketamine) significantly decreased, and Fentanyl-Citrate significantly increased, blood pressure. Fentanyl-Droperidol produced no substantial blood pressure change. Guinea pigs anesthetized with Fentanyl-Citrate and Fentanyl-Droperidol demonstrated significant blood pressure increases when exposed to noise, with the Fentanyl-Citrate group showing a greater response. Animals anesthetized with Ketamine Hydrochloride exhibited no significant blood pressure changes when exposed to the noise.