Transcutaneous electrical nerve stimulation (TENS) reduces pain through central mechanisms involving spinal cord and brainstem sites. Since TENS acts through central mechanisms, we hypothesized that TENS will reduce chronic bilateral hyperalgesia produced by unilateral inflammation when applied either ipsilateral or contralateral to the site of muscle inflammation. Sprague-Dawley rats were injected with carrageenan in the left gastrocnemius muscle belly. Mechanical withdrawal threshold was tested bilaterally before and 2 weeks after carrageenan injection. After testing withdrawal thresholds at 2 weeks, rats received TENS treatment either ipsilateral or contralateral to the site of inflammation. In each of these groups, rats were randomized to control (no TENS), low frequency (4 Hz), or high frequency (100 Hz) TENS treatment. TENS was applied for 20 min at sensory intensity under light halothane anesthesia. Mechanical withdrawal thresholds were re-assessed after TENS or 'no TENS' treatment. Unilateral injection of carrageenan to the gastrocnemius muscle significantly reduced the mechanical withdrawal threshold (mechanical hyperalgesia) bilaterally 2 weeks later. Either low or high frequency TENS applied to the gastrocnemius muscle ipsilateral to the site of inflammation significantly reversed mechanical hyperalgesia, both ipsilateral and contralateral to the site of inflammation. Low or high frequency TENS applied to the gastrocnemius muscle contralateral to the site of inflammation also significantly reduced mechanical hyperalgesia, both ipsilateral and contralateral to the site of inflammation. Since ipsilateral or contralateral TENS treatments were effective in reducing chronic bilateral hyperalgesia in this animal model, we suggest that TENS act through modulating descending influences from supraspinal sites such as rostral ventromedial medulla (RVM).

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Water quality in eutrophic Lake Tohopekaliga, Florida, improved markedly from 1982 to 1992 as a result of reductions in phosphorus and nitrogen loading to the lake. Annual budgets of water, chloride, phosphorus and nitrogen were constructed for the lake, and indicate it is a sink for phosphorus and a source for nitrogen. Water column concentrations of total phosphorus, soluble reactive phosphorus, total nitrogen, dissolved inorganic nitrogen, and chlorophyll a all declined as external inputs of nutrients decreased. Water column nitrogen: phosphorus ratios have increased, suggesting a probable shift from nitrogen‐ to phosphorus‐limitation. This apparent shift in nutrient limitation status also is supported by comparisons of the mean Trophic State Indices for phosphorus, nitrogen, and chlorophyll a. These improvements in water quality are attributed to the diversion of wastewater treatment plant effluent from the lake, and the increased use of wet retention ponds for stormwater runoff.

Shingle Creek is a major inflow to Lake Tohopekaliga, Florida. Water quality and the trophic status of Lake Tohopekaliga are affected strongly by the water quality of Shingle Creek. This report documents 10 yr of water quality data in Shingle Creek at the lake outfall; for a pre‐ (October 1981–December 1986) and a post‐wastewater discharge (January 1987–September 1991) removal period. Nutrient budgets for the subbasins were calculated from an intensive research program (January 1983–December 1985) to document instream impacts attributable to wastewater, determine the role of the cypress swamp in the middle subbasin, and document relationships between water quality and land uses. Rapid urbanization converted forested uplands and agricultural lands to housing and commercial land use during the study. Stormwater runoff in Florida has been identified as a major pollution source. Treatment of stormwater pollution, through Best Management Practices (BMPs), has been regulated by the State of Florida in this area since 1982. By 1988, 84% of the urban landuse in the upper basin was subject to stormwater treatment prior to being discharged to the creek. Potential increases in urban derived nutrient inputs were offset by stormwater management, and alum treatment and diversion of municipal wastewater. Nitrogen loads, and P loads and variance decreased significantly during the 10‐yr period, despite rapid urbanization in the northern and central subbasins. Nutrient export from the subbasins was influenced by the dominant land use. The middle subbasin contains a swamp that contributed the greatest P and Cl− loads because of the increase in discharge to the swamp from sources other than the canal. The northern urban subbasin received the wastewater discharges and served as a net sink for N and P exported from the subbasin.